On Mon, 2013-02-18 at 12:39 +1100, 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.
You're saying that this is useful for code not needing a kernel with CHECKPOINT_RESTORE enabled. Correct? > > 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 Nope, that wont due. Kernel policy is to have things default n. Have an issue with a config, talk with the distribution you are dealing with. They set the policy of what configs get set for their kernels. > 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) One of the above 3 can probably be worked out. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
