On Mon 16-07-18 11:32:56, Mahesh J Salgaonkar wrote: > One of the primary issues with Firmware Assisted Dump (fadump) on Power > is that it needs a large amount of memory to be reserved. This reserved > memory is used for saving the contents of old crashed kernel's memory before > fadump capture kernel uses old kernel's memory area to boot. However, This > reserved memory area stays unused until system crash and isn't available > for production kernel to use.
How much memory are we talking about. Regular kernel dump process needs some reserved memory as well. Why that is not a big problem? > Instead of setting aside a significant chunk of memory that nobody can use, > take advantage ZONE_MOVABLE to mark a significant chunk of reserved memory > as ZONE_MOVABLE, so that the kernel is prevented from using, but > applications are free to use it. Why kernel cannot use that memory while userspace can? [...] > Documentation/powerpc/firmware-assisted-dump.txt | 18 +++ > arch/powerpc/include/asm/fadump.h | 7 + > arch/powerpc/kernel/fadump.c | 123 +++++++++++++++++-- > arch/powerpc/platforms/pseries/hotplug-memory.c | 7 + > include/linux/mmzone.h | 2 > mm/page_alloc.c | 146 > ++++++++++++++++++++++ > 6 files changed, 290 insertions(+), 13 deletions(-) This is quite a large change and you didn't seem to explain why we need it. -- Michal Hocko SUSE Labs
