blcr-dkms 0.8.5-2.1 / usr / src / blcr-0.8.5 / NEWS

This file lists the significant user-visible changes between releases
of BLCR, including main features and bug fixes.

0.8.5
-----------
January 29, 2013
Bug fix and expanded-support release.
 - This release fixes the following user-visible bugs and "issues"
   + This release adds support for "vanilla" Linux kernels up to 3.7.x
   + Fixes "vdso remap failed" errors on x86 platforms.
   + Fixes support for Xeon Phi
   + Fixes support for ARMv7 CPUs and for ARM THUMB2 kernels
   + Fixes to work with more recent autotools, glibc, rpmbuild, etc...
   + Fixes for memory regions larger than 4G
   + Numerous other minor bugs
 - RPM packaging improvements
   + Now supports "rpmbuild --define 'with_multilib 0' ..." to disable
     building of 32-bit libs on 64-bit targets.
   + "make rpms" now works correctly when run in non-English locales
 - This release is known NOT to work with 3.8.x kernels

0.8.4
-----------
October 11, 2011
Bug fix and expanded-support release.
 - This release fixes the following user-visible bugs and "issues"
   + This release adds support for "vanilla" Linux kernels up to 2.6.38.
   + This release adds support for recent RHEL5 kernels.
   + Occasional "random" failures on x86 have been identified and fixed.

0.8.3
-----------
August 15, 2011
Bug fix and expanded-support release.
 - This release fixes the following user-visible bugs and "issues"
   + More options for dealing with BLCR-vs-NSCD conflicts.  See the BLCR
     FAQ entry 'Why do I get "vmadump: mmap failed: /var/db/nscd/[something]"
     in the system logs?' for a list of one's options.
   + This release adds support for "vanilla" Linux kernels up to 2.6.34.
   + bug 2594 - dpipe.ct and forward.ct fail "while restoring external pipe"
 - This release has known issues some RHEL5-derived kernels.  Specifically,
   + auditing cr_restart can cause a kernel BUG() message to be issued
   + the vdso page is misidentified during restart of 32-bit
     processes on x86_64 kernels.  You'll see the following error:
     do_mmap(0, ffffe000, 00001000, ...) = 0xfffffffffffffff4 (failed)
   + --save-all is not supported for restart of 32-bit processes on x86_64
     kernels.  If you try to restore such a process, you'll see cr_restart
     will fail with the error:
     Failed to locate newborn mmap()ed space
   A patch for the RHEL5 kernels that addresses these issues is available on 
   the web site:
   https://upc-bugs.lbl.gov/blcr-dist/blcr-0.8.3+kernel-2.6.18.el5.patch01
   We haven't fully tested the rhel5 patch on non-el5 kernels (that's why it's 
   not in the release), so we recommend you apply the RHEL5 patch ONLY if you
   are running a 2.6.18 el5 kernel.

The next release, BLCR 0.8.4, will merge support for RHEL5 kernels, and add
support for 2.6.35 kernels.

0.8.2
-----------
June 16, 2009
Bug fix and expanded-support release.
 - This release adds support for 2.6.30 kernels
 - This release fixes the following user-visible bugs and "issues"
   + "waitpid(0)" error when restarting a process that was a child of init
   + A race that would infrequently cause an abnormal restart to hang

0.8.1
-----------
March 25, 2009
Bug fix and expanded-support release.
 - This release adds support for 2.6.29 kernels.
 - The final known xen-specific bug (2457) has been found to be a Xen bug.
   Xen 3.1.2 or newer is recomended when using BLCR.
 - This release makes the following libcr API additions/changes:
   + Increase CR_MAX_CALLBACK from 32 to 32 million.
 - This release adds additional error checking and improved documentation
   for error cases for the following libcr functions:
   + cr_register_callback()
   + cr_replace_callback()
   + cr_register_hook()
 - This release fixes the following user-visible bugs and "issues"
   + 2508 - inconsistent metadata from a networked file system
   + 2520 - possible deadlock when using some functions with critical sections
   + 2524 - restart-time SEGV on powerpc with 2.6.15 or older kernel
   + 2525 - process deadlock on checkpoint after restart
   + 2526 - process deadlock between omit and forward operations
   + C++ scoping problem for "struct cr_rstrt_relocate_pair"
   + Correct a bug that would reset the persist count across checkpoints
   + Prevent "stuck" tests when TOSTOP bit is set in termios.c_lflag.
   + Correct flaws in tests "prctl" and "stage0002" that could yield false
     failures under certain conditions

0.8.0
-----------
January 12, 2009
Enhanced functionality and expanded-support release.
 - This release adds support for 2.6.26, .27 and .28 kernels.
 - In this release support for Xen is no longer considered experimental.
   However, there is still one known xen-specific bug (2457) in which
   the FPU state may become corrupted w/ paravirtualized kernels.
 - In this release the majority of checkpoint I/O is performed using
   O_DIRECT when available, significantly reducing the cost of checkpointing
   any process which uses a large fraction of the physical memory.
 - This release includes an unfinished port to SPARC64, contributed by
   Vincentius Robby <vincentius@umich.edu> and Andrea Pellegrini
   <apellegr@umich.edu>.  Anyone willing/able to help complete this port
   should contact checkpoint@lbl.gov.
 - As previously announced, this release removes support for 2.4.x kernels
   that contain backported NPTL support (e.g. RH9 and RHEL kernels).  Support
   for all other 2.4.x kernels was removed in 0.7.0.
 - This release merges the blcr_vmadump kernel module into the blcr module.
 - This release adds preliminary support for the "Fault Tolerance Backplane"
   (FTB).  See README.FTB for more information.
 - This release adds the following features to the cr_checkpoint utility:
    + --kmsg-{none,error,warning} options to control reporting of kernel-level
      errors and warnings messages when taking a checkpoint.
 - This release adds the following features to the cr_restart utility:
    + --kmsg-{none,error,warning} options to control reporting of kernel-level
      errors and warnings messages when restarting from a checkpoint.
    + --[no-]restore-{pid,pgid,sid} options to control restore of the
      process id, process group id, and session id.  The default remains as
      in prior releases: restore only pid.
 - This release makes the following libcr API additions/changes:
    + The following functions were announced in May 2008 as scheduled for
      removal in 0.8.0.  They have not been removed, but have been marked
      with gcc's "deprecated" attribute to produce a compiler warning if used.
       * cr_request()
       * cr_request_file()
       * cr_request_fd()
    + These functions have been added for controlling checkpoint requests:
       * cr_wait_checkpoint()
       * cr_reap_checkpoint()
       * cr_log_checkpoint()
       * cr_poll_checkpoint_msg()
      The wait and reap functions expose independently the two steps taken in
      the existing cr_poll_checkpoint() function.  The log function collects
      kernel-level error or warning messages if called between wait and reap.
      The poll...msg() function is a convenience function, documented and
      implemented in terms of the wait, log and reap functions.
      The cr_poll_checkpoint() function will remain in libcr, but is now
      documented and implemented in terms of cr_poll_checkpoint_msg().
    + A new CR_CHKPT_ASYNC_ERR flag to cr_request_checkpoint() defers the
      reporting of almost all errors in a call to cr_request_checkpoint()
      until the call to cr_reap_checkpoint() or cr_poll_checkpoint[_msg]().
    + The following functions have been added for making restart requests
      via library calls, rather than using the cr_restart utility.  These
      are all marked "EXPERIMENTAL" as there might be significant changes
      to these calls in the future.
       * cr_initialize_restart_args_t()
       * cr_request_restart()
       * cr_wait_restart()
       * cr_reap_restart()
       * cr_log_restart()
       * cr_poll_restart_msg()
       * cr_poll_restart()
    + The struct members "old" and "new" in struct cr_rstrt_relocate_pair
      have been renamed to "oldpath" and "newpath".  This change was required
      because "new" is a C++ reserved word.
   See the comments in include/libcr.h for API documentation.
 - This release makes the following additions/changes to the BLCR test suite:
    + Add tests of many of the features new to this release
    + Add new tests, or cases to existing tests, for reproducing several
      of the bugs fixed in this release.
    + Fix command lines used in several tests to function correctly when
      "POSIXLY_CORRECT" is set in the environment
    + Recode crut_wrapper and seq_wrapper in C, rather than perl, to allow
      running the full testsuite in environments without perl (such as
      embedded ARM platforms).
 - This release fixes the following user-visible bugs and "issues"
    + 2021 - Provide extended error reporting mechanism
    + 2056 - Eliminate perl wrappers
    + 2287/2437 - Xen segment selector problems
    + 2292 - --restore-ids does not work correctly for multithreaded processes.
    + 2317 - implement "async" request errors 
    + 2318 - checkpoint hangs after SEGV
    + 2322/2446 - Failure when stack limit is too big
    + 2344 - bad cr_restart usage causes kernel oops
    + 2453 - loss of sigaltstack across restart
    + 2454 - Oops in FPU restore
    + Address bug 2448 - there may have been a race with cr_close_other()
    + Fix ENOMEM when checkpointing processes with no supplementary group IDs
    + i386 FPU restore code would fail to notice corrupt i387 state
    + Fix a bug in the ARM atomics
    + Fix several issues with restart of 64-bit processes with a 32-bit
      requester, as exposed by the addition of cr_request_restart() to libcr.

0.7.3
--------
August 12, 2008
Bug fix release
 - Fix a kernel Oops on a rarely run error path.
 - Fix a in-kernel memory leak when restoring unlinked files.
 - Fix a file descriptor leak when cr_request_checkpoint() failed.
 - Fix fsync() handling to allow checkpoints to /dev/null
 - Fix bug 2309: cr_enter_cs() fails because of previous cri_info_free().
   This bug was resolved by adding two new functions:
     cr_inc_persist() and cr_dec_persist()
   See comments in libcr.h for a description and usage.
 - Fix bug 2311: vmadump_thaw_proc() returns -513.
 - Fix bug 2315: ENOMEM with processes with zero supplementary group IDs.
 - Fix bug 2316: "mkdir: file exists" module installation problem.

0.7.2
--------
July 28, 2008
Bug fix release
 - Fix a logic error in use of kernel-level synchronization primitives.
 - Fix a 32-bit VDSO restore bug on x86-64 2.6.23 and 2.6.24 kernels.
 - Fix a kernel Oops seen with RH9 2.4.x kernels
 - Fix bug 2298: compile error cr_io.o on SLES10sp2
 - Fix bug 2300: restart fails for open file >2GB
 - Fix bug 2302: block all signals in internal thread

0.7.1
--------
June 25, 2008
Bug fix and expanded-support release
 - Fix (part of) bug 2263, allowing nested use of cr_run.
 - Fix bug 2251, allowing use of HUGETLB_MORECORE=y with libhugetlbfs.
 - Fix bug 2295 (restart failure w/ heap > 4GB).
 - Fix sporadic EPERM failures when checkpointing encounters a zombie proc.
 - Add support for 2.6.26-rc7 kernel.
   While we don't officially support -rc<N> kernels, it is hoped that
   these changes will be sufficient to support the final 2.6.26.
 - Add cr_hold_ctrl(), allowing control over the thread hold behavior.
   This is required to restore the 0.6.X behavior for at least one
   application that would deadlock with the 0.7.X default behavior.

0.7.0
--------
May 30, 2008
Enhanced functionality and expanded-support release.
 - This release adds support for 2.6.25 kernels.
 - This release adds EXPERIMENTAL support for 32-bit PPC platforms.
 - This release adds EXPERIMENTAL support for Xen-enabled kernels (both
   dom0 and domU).  In our testing so far it either works great or not
   at all, depending on the installation.  We have not yet identified
   what distinguishes the working systems from the broken ones, and
   would appreciate feedback on your success or failure using BLCR
   with Xen-enabled Linux kernels.
 - As previously announced, this release removes support for 2.4.x kernels
   with the current exception of the RH9 and RHEL kernels (and derivatives)
   that contain backported NPTL support.  These too may be removed in the
   not too distant future.
 - As previously announced, this release begins the removal of support for
   LinuxThreads.  If you are using LinuxThreads you may experience random
   failures in the BLCR testsuite and with your own multithreaded apps.
   New interest in using BLCR with non-GNU libc may lead to a return of
   LinuxThreads support.  Please contact us if you have interest it this.
 - This release adds the following features to the cr_checkpoint utility:
    + --quiet option to suppress output from cr_checkpoint
    + --noclobber option (don't disturb existing files)
    + Options for treatment of ptrace() child and parent processes:
       --ptraced-{error,skip,allow}
       --ptracer-{error,skip}
    + Options to save/restore executables and libraries in context files:
       --save-{exe,private,shared,all,none}
   See the cr_checkpoint manpage for more details on each of these.
 - This release adds the following features to the cr_restart utility:
    + --quiet option to suppress output from cr_restart
      Previously there was no way to do so without also losing the output
      of the restarted process(es).
    + Add --run-on-* family of options to provide user-specified error
      handling hooks.  Previously there was no way to automatically/safely
      distinguish a failure of cr_restart from a non-zero exit from the
      restarted application.  This resolves bug 1974.
    + Add --relocate option to enable restart-time replacement of file and
      and directory paths saved in the context file.
    + Add --fd option to restore from an open fd, rather than a file.
   See the cr_restart manpage for more details on each of these.
 - This release adds the following feature to the cr_run utility:
    + --omit option to run a process with BLCR support such that the
      process (and its descendants) will be omitted from checkpoints.
 - This release makes the following libcr API additions/changes:
    + cr_forward_checkpoint() is fully tested and thus no longer labeled
      as "use at your own risk".  Its documentation in libcr.h is now
      complete as well.
    + cr_register_hook() is fully tested and thus no longer labeled
      as "use at your own risk".
    + As anticipated in previous releases, the error code returned from
      cr_poll_checkpoint() has CHANGED for the case of restarting from a
      checkpoint of oneself.  This may break existing code that will not
      be prepared for the new errno value.  However, the previous value
      of EINVAL could have masked actual invalid-argument errors.
      The alternative of returning 0 (success) was considered, but was
      discarded because it was deemed valuable to be able to reliably
      distinguish whether one was continuing or restarting from a
      checkpoint of oneself.
    + As alternatives to CR_ETEMPFAIL and CR_PERMFAIL, authors of BLCR
      callbacks can now specify the errno values to be returned to the
      checkpoint requester on a case-by-case basis.
    + cr_tryenter_cs() has been added as a non-blocking alternative to
      the cr_enter_cs() function.
    + Several functions that would previously respond to usage errors
      with an abort() or an undefined behavior now return -1 with one of
      two new values of errno:
       * CR_ENOINIT  - caller has not made the required call to cr_init()
       * CR_ENOTCB   - call is only valid from a checkpoint callback
    + The following functions are marked as deprecated:
       * cr_request()
       * cr_request_file()
       * cr_request_fd()
      They do not provide any mechanism to specify the checkpoint scope
      or to detect errors.  They are currently implemented as (awkward)
      wrappers around cr_request_checkpoint() and cr_poll_checkpoint().
      They are scheduled to be removed in 0.8.0.
   See the comments in include/libcr.h for API documentation.
 - This release introduces two "stub" libraries: libcr_run and libcr_omit.
   They differ from the "full" libcr library in that they contain only a
   BLCR signal handler and the initialization code to register it.  They
   do not include any of the entry points declared in libcr.h, and the
   handler code does not run any callbacks.
   The cr_run utility now uses these libraries in LD_PRELOAD variable,
   rather than the full libcr.so used in previous releases.
   See the BLCR User's Guide for information on using these libs.
 - This release makes several additions to the BLCR test suite, including
   tests of most of the features new to this release and some motivated by
   bugs fixed in this release.  Many existing tests have been expanded to
   exercise additional corner cases.
 - This release makes the following changes to "configure" behavior:
    + The --with-linux= option now accepts a kernel revision (the output
      or "uname -r") as a value, causing configure and search for that
      revision in some standard locations.  This is intended to make it
      easier and less error prone to specify for which kernel to build.
      In most modern distributions, this single option will be sufficient
      to configure BLCR for any installed kernel.
    + Previously --with-linux= would be used to specify a kernel source 
      directory, and if needed --with-linux-obj= could be given to help
      find the corresponding build directory.  With this release the
      role of --with-linux= as changed to be that of a build directory
      and the option --with-linux-src= is available if the sources can't
      be found automatically.
    + The configure-time probes of the kernel headers and configuration
      are now performed using the full CFLAGS/CPPFLAGS from the Linux
      kbuild infrastructure.  This ensures proper configuration with
      Xen-enabled kernels that prepend Xen-specific components to the
      include path.
    + At configure time one can set KCC to specify that the kernel
      modules are to be built with a different C compiler than the
      user-space components of BLCR.
 - On the ARM platform, the "good enough for LinuxThreads" implementation
   of atomic operations has been replaced with truly atomic ops based
   on the kernel-level support added for NPTL.
 - As a temporary work-around for bug 2251, BLCR will currently refuse
   to checkpoint processes with files on hugetlbfs mmap()ed with the
   MAP_PRIVATE flag.  This is to avoid potentially serious instability
   that may result if BLCR attempts to checkpoint such a process.
 - Fixes the following user-visible bugs and "issues"
    + 1974 - Make it possible to decide whether a restart succeeded
    + 2023 - ARM atomics need update
    + 2042 - libcr.so not linked to libc
    + 2124 - Make check fails at pid_in_use.st
    + 2214 - close cri_live_count race
    + 2216 - Move post-restart signal delivery to post-callback
    + 2247 - BLCR assumes 64-bit gcc on 64-bit arch
    + 2248 - Separate CC and KCC
    + 2265 - CR_CHECKPOINT_OMIT generates 0 byte context file
    + 2266 - process doing CR_CHECKPOINT_TEMP_FAILURE is killed!
    + 2271 - cr_checkpoint --clobber fails to overwrite file
    + 2272 - cr_get_restart_info returns wrong src path
    + 2274 - Invalid (zero or huge) pids seen at restart time
    + Remove bash-specific assumptions in the tests
    + Stronger validation of BLCR against proper kernel version
    + Validation of BLCR's kernel module versions against each other
    + Performance improvements from better memory management and
      from coalescing of background work.
    + Preserve error codes for I/O errors.  Previously any error
      from a read/write at kernel level was reported as EIO.  Now
      the original errors (such as ENOSPC) are preserved.
    + Several others found by internal testing or reported by email
      and fixed without assigning bug numbers.
 - The file contrib/blcr.magic contains the format description needed
   by the "file" utility to identify BLCR's context files.

0.6.5
--------
February 29, 2008
Bug-fix release.
 - This release fixes a bug that could corrupt the kernel's pid hash
   data structures if a restart failed due to a pid conflict on
   kernels 2.6.17 and newer.
 - This release fixes a use-after-free bug in the code for aborting
   a checkpoint that could have caused a kernel Oops.

0.6.4
--------
January 28, 2008
Bug-fix and expanded-support release.
 - This release adds support for 2.6.24 kernels.
 - This release fixes bug 2234 which could cause a kernel Oops when
   dealing with mmap()s of HUGETLBFS on some kernels.

0.6.3
--------
January 22, 2008
Bug-fix release.
 - This release fixes bug 2001 which was causing intermittent floating-
   point register corruption on x86-64, even after BLCR was unloaded.

0.6.2
--------
January 14, 2008
Bug-fix and expanded-support release.
 - This release adds support for 2.6.23 kernels.
 - This release adds support for SuSE's 2.6.22.x kernels.
 - This release fixes a file descriptor leak that occurred on restart from
   a checkpoint-of-self requested via cr_request_checkpoint().
 - This release fixes a deadlock (and unkillable process(es)) when a
   multi-threaded process aborts (or omits itself from) a checkpoint
   under certain conditions.
 - This release fixes a restart-time failure when a checkpoint includes a
   pipe with one end outside the checkpoint scope, and data is buffered
   in the pipe.
 - This release fixes a bug with the cr_request{,_file}() calls in which
   a failed checkpoint would cause failure of the next one if it had the
   same destination file name.
 - This release fixes a race condition with the cr_enter_cs() and checkpoints
   in multi-threaded processes.
 - This release fixes post-checkpoint signal delivery (--stop and friends)
   to occur after the checkpoint is fully completed.  See bug 2201 for
   a full description of the problems addressed by these changes.
 - This release documents (and fully implements) signal-delivery options
   to cr_restart (see bug 2200).
 - This release fixes two kernel Oopses (bugs 2222 and 2223) due to races
   against processes/threads that are exiting.
 - Adds test cases for most of the bugs fixed in this release.
 - Minor improvements/changes to documentation
 - Other minor bug fixes

0.6.1
--------
September 25, 2007
Bug-fix release
 - This release resolves build and run-time issues seen on Debian "sid".
 - This release eliminates the need to manually set __LINUX_ARM_ARCH__ at
   configure time (ARM platform only).
 - This release fixes a file descriptor leak that occurred on failure of a
   checkpoint requested using any of the cr_request{,_file,_fd}() calls.
 - This release fixes a race condition and a LinuxThreads incompatibility
   in the "hooks" test (which is not run by default).

0.6.0
--------
September 10, 2007
Functionality and expanded-support release.
 - This release adds support for 2.6.22 kernels.
 - This release includes experimental support for PPC64 platforms
    + PPC64 supports both 32- and 64-bit applications.
    + No support for 32-bit kernels.
      Contact us if you would like to help w/ a PPC32 port.
    + No support for 2.4.x kernels
    + Tested with NPTL and kernels 2.6.12 (Gentoo) and 2.6.18 (FC6)
    + There are known problems with BLCR with LinuxThreads on PPC64
 - This release includes experimental support for ARM platforms.
    + Tested only for 2.6.12 and newer kernels
    + Thanks to Anton V. Uzunov <anton.uzunov@dsto.defence.gov.au>
      of the Australian Government Department of Defence, Defence
      Science and Technology Organisation for contributing this port.
    + ARM-specific questions should be directed to blcr-arm@hpcrd.lbl.gov
 - This release includes experimental support for cross-compilation.
    + See config/cross_helper.c for information on cross-compilation.
    + This has been tested only in the context of the ARM port
    + Thanks to Anton V. Uzunov for motivating and testing this work
 - This release includes a new API for issuing a checkpoint request.
    + Allows a program to request a checkpoint without the need to invoke
      system("cr_checkpoint ...").
    + See comments in include/libcr.h for information on the following:
      cr_initialize_checkpoint_args_t()
      cr_request_checkpoint()
      cr_poll_checkpoint()
 - This release adds a mechanism (CR_CHECKPOINT_OMIT) for processes to
   exclude themselves from a checkpoint (useful for batch-system helper or
   shepherd processes).
 - This release makes cr_checkpoint and cr_restart utilities checkpointable
 - This release adds full support for mmap()-based shared memory
    + Repairs the loss of sharing that existed in 0.5.x releases
    + Supports hugetlbfs
 - This release adds full support for save/restore of pending signals.
 - Default scope of cr_checkpoint is now --tree, rather than --pid.
 - Now checkpoint/restart unlinked open files.
 - Revised handling of certain file-descriptors at restart:
   + No longer override "normal" files with correspondingly-numbered fds
     from cr_restart as that consistently breaks shell "here documents".
   + Restore pipes endpoints that lie outside the checkpoint scope by
     attaching them to stdin or stdout of cr_restart, rather than to its
     correspondingly-numbered fds.
   + Opens of a process's controlling tty are attached to "/dev/tty" at
     restart, even if they were open by their "exact" name at checkpoint
     time (e.g.  "/dev/pts/0").
 - Experimental support for relocatable kernels on x86 and x86-64
 - Expanded test-suite
 - Option to install the testsuite (--enable-testsuite)
 - Support "install-strip", "install-exec" and "install-data" make targets
 - Tested against many scripting and programming language environments:
   + shells:  ash, bash, (t)csh, (pd)ksh and zsh
   + scripting-type languages: perl, python, tcl/expect, ruby and guile
   + java runtime environments: Sun, IBM and GNU
   + misc. language runtimes: php, rep, clisp, emacslisp, gst, ocaml and sml
   + Run "make bonus-tests" to run these tests on your own machine, but be
     warned that the tests themselves are fragile (contain races) and may
     experience random failures.  However, please do report any tests that
     fail consistently.
 - Many minor bug fixes and code cleanups

July, 2007 - DEPRECATED support for LinuxThreads and for Linux 2.4.X kernels
 - Starting with the 0.6.0 release, new bug reports that one cannot reproduce
   under NPTL + Linux 2.6.x will receive little or none of our attention.
   However, we will try to distribute user-contributed fixes for such bugs.
   Note that the 0.6.0 release *does* pass the BLCR test-suite under
   LinuxThreads and/or 2.4.x kernels on the developers' x86 systems.
   However, we have seen test failures on PPC64 when running LinuxThreads
   with a 2.6.12 kernel (Gentoo distro).
 - Beginning with the next "full" release (0.7.0) we will begin to remove
   code in BLCR that exists only to support LinuxThreads and/or Linux 2.4.x.
 - We have not yet decided the fate of support for those 2.4.x kernels which
   include Red Hat's backport of NPTL support (RHL9.0, RHEL, RHAS, etc.).
 - If anybody cares enough about 2.4.x and/or LinuxThreads to volunteer to
   take over testing and maintenance of BLCR on such platforms, let us know.

0.5.6
--------
July 11, 2007
Bug-fix release.
 - Fix a bug that could incorrectly restore data buffered in a pipe.

0.5.5
--------
April 27, 2007
Expanded-support release.
 - This release adds support for 2.6.21 kernels.

0.5.4
--------
April 20, 2007
Bug-fix release.
 - Multiple bug fixes, including:
   + Bug 1972: Restart pid-conflict could cause kernel Oops
   + Bug 1977: Unintended 2GB limit on application working set
   + Compilation problems on some x86_64 kernels (map_vsyscall undefined)

0.5.3
--------
March 29, 2007
Bug-fix release.
 - Multiple bug fixes, including:
   + Bug 1961: Checkpoint of zombie yields kernel Oops.
   + Bug 1967: Restart failed: Bad address
   + Unkillable cr_restart if multi-threaded restart failed due to pid in use.

0.5.2
--------
March 23, 2007
Bug-fix release.
 - Multiple bug fixes, including:
   + Bug 1949: cr_request*() functions need original context file to restart
   + Bug 1954: "cr_checkpoint -T" yields "invalid option"
   + Bug 1955: mmap(PROT_READ, MAP_SHARED) broken for read-only files
 - Add "with_autoreconf" option to rpm specfile.

0.5.1
--------
March 20, 2007
Expanded-support and minor improvement release.
 - Expanded kernel coverage
   + Add support for 2.6.17-5mdv and its updates (Mandriva 2007)
   + Add support for 2.6.20
 - Fix -fstack-protector problems w/ the .src.rpm on FC6
 - Eliminate harmless undefined symbol warnings from MODPOST

0.5.0
--------
March 2, 2007
Functionality and expanded-support release.
 - Expanded kernel coverage
   + 2.6.0 through 2.6.19 for x86 and x86_64
   + 2.4.0 through 2.4.34 for x86 only
 - Multi-process support (related processes and associated pipes)
   + See BLCR_Users_Guide.html and the cr_checkpoint man page
 - Support for 32-bit apps on 64-bit kernels
   + See "--enable-multilib" in BLCR_Admin_Guide.html
 - Support for directories opened with opendir()
 - Support for open()s of /dev/{null,zero,full,random,urandom}
 - Support for checkpoints on Luster file systems
   + Contributed by Dean Luick <luick@cray.com>
 - Support for building static libcr
   + Contributed by Dean Luick <luick@cray.com>
 - Fixes to many distclean problems
   + Issues identified by Dean Luick <luick@cray.com>
 - I/O aggregation for improved performance
   + Contributed by Qi Gao <qaoq@cse.ohio-state.edu>
 - Additional examples and test cases
 - API addition: cr_get_restart_info()
 - "Retool" of configure code for ease of addition/maintenance
 - Numerous bug fixes, including:
   + Bug 1240: pid leak on restart failure
   + Bug 1396: SIGPIPE when restarting w/ stdin/out from/to a pipe
   + Bug 1640: context files > 2GB require O_LARGEFILE 
   + Bug 1662: context files open R/W leads to restart failure
   + Bug 1669: checkpoint to a socket fails
   + Bug 1807: unrecognized warning suppression flag passed to gcc
   + Bug 1854: libcr link failure w/ stack-protection-enabled gcc
   + Bug 1925: link failure w/ pthread_atfork() on some glibc versions
   + Bug 1933: crash restoring dup of ignored fd (socket or chrdev)
   + Incorrect treatment of certain anonymous mmap() cases
   + MAP_SHARED mmap()ed regions would become MAP_PRIVATE upon restart
     * NOTE: We still fail to restore any sharing among processes
       when using MAP_ANONYMOUS or when mapping an unlinked file.
       However, children fork()ed after a restart will now correctly
       share with their parent.
       FIXING THE LOST SHARING IS A HIGH-PRIORITY ITEM FOR 0.6.0
   + Wrong parent for restored orphans (children of init)
   + dup()ed file descriptors always restored together

0.4.2
--------
November 22, 2005
Functionality and bug-fix release.
 - 2.6.x kernel support "stable"
 - x86_64 support "stable" (but there is no support for 32-bit apps)
 - Multiple bug fixes (some critical)

0.4.1_b5
--------
October 10, 2005
BETA bug-fix release.
 - Multiple bug fixes (some critical)

0.4.1_b4
--------
August 24, 2005
BETA bug-fix release.
 - Multiple bug fixes (some critical)

0.4.1_b3
--------
July 29, 2005
BETA bug-fix and functionality release.
 - Fix inter-module dependencies under 2.6 kernels.
 - Fix empty /etc/init.d/blcr in rpms

0.4.1_b2
--------
July 6, 2005
BETA bug-fix and functionality release.
 - Opteron support completed (but experimental).
 - Improved coverage of 2.6.x kernels (still considered experimental):
   + At least minimal testing under SuSE 9.{2,3} and Fedora Core {2,3,4}
   + Example init script updated for 2.6.x
   + Updates to Admin Guide for Fedora-isms
 - Fixed file truncation bug
 - Fixed signal trampoline bug with RHAS
 - Support for Scalable Systems Software advanced to Fedora Core 2
 - Some "dirty tricks" have been reimplemented with cleaner solutions:
   + New method for syscalls that bypass glibc
   + Better-supported signal trampolines (work w/ gcc 2.96 through 4.0.0)
   + More robust mechanism for module symbols (linker rather than cpp)
   + More robust mechanism for restart time thread creation
 - Cleanups of .spec file to work w/ latest rpm version.

0.4.1_b1
--------
Not publicly released.

0.4.0
-----
February 18, 2005
Functionality release.
 - Add experimental support for Linux 2.6.x kernels.
 - Many changes as part of an in-progress Opteron port (incomplete).

0.3.1
-----
December 1, 2004
Bug-fix release.
 - Fix a bug which rendered cr_run useless for most applications.
 - Add athlon support to the RPM specfile and generally improve cpu
   support in the specfile by honoring --target.
 - Fix a race condition in pthreaded tests with LinuxThreads.
 - Minor improvements to Admin Guide, including fixing a confusing typo.

0.3.0
-----
November 8, 2004
Functionality release.
 - Files support is now enabled by default and no longer "experimental".
 - Support for Scalable Systems Software (http://sss-oscar.sf.net).
 - Fix libcr.so to allow use via dlopen().
 - Many small bug fixes.
 - Security fix related to LDT/TLS restore.
 - Support for more kernel versions, including RHEL3 and CentOS 3.1
 - Much more robust configuration-time checking of kernel headers.
 - Runtime version checking between user space and kernel module.
 - More informative error from cr_checkpoint when target process
   lacks checkpointing support.

0.2.4 and 0.2.5
---------------
Snapshots for SSS-OSCAR testing.  Not publicly released.

0.2.3
-----
April 30, 2004
Bug-fix release.
 - Fixed compilation error that occurred with --enable-trace.
 - Updated timeout thread to handle new DEAD state in 2.6 kernel (also in some
   recent 2.4 RedHat kernels).

0.2.2
-----
April 23, 2004
Bug-fix release.
 - Fixed bug with --enable-files support: regular file handles now
   saved/restored across checkpoint correctly.

0.2.1
-----
December 05, 2003
Bug-fix release.
 - Fix compilation problems with certain kernels and compilers.
   Now known to compile with kernel.org kernels as old as 2.4.0
   and as new as 2.4.23.
    - Tested against kernels as old as a RedHat 2.4.7-10 and as new as a
      RedHat 2.4.20-24.9.
    - Tested w/ gcc 2.96, 3.2, 3.2.2 and 3.3.1.
 - Fix vfork() problem which was causing "cr_run make" (or "make"
   with LD_PRELOAD set) to fail.
 - Fix problem where processes restored under 2.4.23 could not
   subsequently be ptraced or dump core.
 - Strip debugger bloat from kernel modules.
 - Fixed locking problems which prevented experimental files code
   from compiling against SMP kernels.
 - Make the rpm spec file more easily reusable for different kernels.
 - Modules now include proper version and contact info in syslog.
 - Proper use count is now kept by modules.

0.2.0
-----
November 20, 2003
Initial public release.