Messages in this thread | | | Date | Mon, 31 Aug 2009 11:27:07 +0800 | From | Amerigo Wang <> | Subject | Re: [Patch 0/8] V5 Implement crashkernel=auto |
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Michael Ellerman wrote: > On Wed, 2009-08-26 at 23:15 -0400, Amerigo Wang wrote: > >> V4 -> V5: >> - Rename the global functions, as suggested by Andrew. >> - Save some macros, as suggested by Andrew. >> - Change the high threshold, from 32G to 4G. >> - Change the low threshold on ppc, suggested by ppc developers. >> - Make the mm part as a seperate function, suggest by Eric. >> - Make the IA64 code more readable. >> - Reorder the patchset again, since review from mm people is done. >> >> V3 -> V4: >> - Reorder the patches. >> - Really free the reserved memory, instead of remapping it. >> (Thanks to KAMEZAWA Hiroyuki!) >> - Release the reserved memory resource when the size is 0. >> - Use strict_strtoul() instead of simple_strtoul(). >> >> V2 -> V3: >> - Use more clever way to calculate reserved memory size, especially for IA64. >> - Add that patch that implements shrinking reserved memory >> >> V1 -> V2: >> - Use include/asm-generic/kexec.h, suggested by Neil. >> - Rename a local variable, suggested by Fenghua. >> - Fix some style problems found by checkpatch.pl. >> - Unify the Kconfig docs. >> >> This series of patch implements automatically reserved memory for crashkernel, >> by introducing a new boot option "crashkernel=auto". This idea is from Neil. >> >> In case of breaking user-space applications, it modifies this boot option after >> it decides how much memory should be reserved. >> >> On different arch, the threshold and reserved memory size is different. Please >> refer patch 7/8 which contains an update for the documentation. >> >> Patch 8/8 implements shrinking reserved memory at run-time, which is useful >> when more than enough memory is reserved automatically. >> >> This patchset _is_ already tested on x86_64, IA64 and ppc64. >> > > I don't want to sound like a micro-kernel zealot, I'm not, but I'm still > unconvinced as to why the auto logic needs to go in the kernel. What is > the compelling reason that the kernel needs to do this calculation vs > some userspace tool? We already have the syntax that allows defining a > different crash size depending on the size of RAM. >
Take a look at the x86 part, it can not be done _directly_ in kernel command line with the syntax.
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