Messages in this thread | | | Subject | prctl(PR_SET_MM) | Date | Mon, 18 Feb 2013 12:39:54 +1100 (EST) | From | (Amnon Shiloh) |
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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)
Thank you, Amnon.
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