Messages in this thread | | | Date | Sun, 17 Feb 2013 21:44:07 -0800 | From | Randy Dunlap <> | Subject | Re: prctl(PR_SET_MM) |
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On 02/17/13 17:39, Amnon Shiloh wrote: > Hello, > > The code in "kernel/sys.c" provides the "prctl(PR_SET_MM)" function, > which is the only way a process can set or modify the following 11 > per-process fields: > > start_code, end_code, start_data, end_data, start_brk, brk, > start_stack, arg_start, arg_end, env_start, env_end. > > Being able to set those fields is important, even crucial, > for any conceivable user-level checkpointing software, as > well as for migrating processes between different computers. > > Unfortunately, this code (essentially "prctl_set_mm()") is presently > enclosed in "#ifdef CONFIG_CHECKPOINT_RESTORE" which is configured > as "default n" in "init/Kconfig". Many system-administrators who > may like to have a checkpoint/restore or process-migration facility, > but use standard pre-packaged kernels, find the requirement to > configure and compile their own non-standard kernel difficult or > too prohibitive. > > Would it be possible to have this code enabled by default? > > This could be done in one of 4 ways: > 1) Having CONFIG_CHECKPOINT_RESTORE enabled by default; or > 2) Releasing this code from the "#ifdef CONFIG_CHECK_RESTORE"; or > 3) Placing this code within a different kernel-configuration option > (say "CONFIG_BASIC_CHECKPOINTING") that is enabled by default; or > 4) Placing this code under a dual #if, so instead of: > #ifdef CONFIG_CHECKPOINT_RESTORE > have: > #if defined(CONFIG_CHECKPOINT_RESTORE) || defined(CONFIG_BASIC_CHECKPOINTING)
This is basically a distro issue. Distros can choose to enable this code by default, but the Linux kernel that Linus maintains does not need to enable it.
-- ~Randy
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