On Tue, 18 Aug 2009 14:31:23 +0800
Amerigo Wang <amwang@xxxxxxxxxx> wrote:
Hi, thank you!I see.
Can I have a question ?Use bootmem, I think.
- How crash kernel's memory is preserved at boot ?
In x86,
setup_arch()
-> reserve_crashkernel()
-> find_and_reserve_crashkernel()
-> reserve_bootmem_generic()
Then, all "active range" is already registered and there are memmap.
It's hidden from the system before mem_init() ?Not sure, but probably yes. It is reserved in setup_arch() which is before mm_init() which calls mem_init().
Do you have any advice to free that reserved memory after boot? :)
Let's see arch/x86/mm/init.c::free_initmem()
Maybe it's all you want.
- ClearPageReserved()
- init_page_count()
- free_page()
- totalram_pages++
But it has no argumetns. Maybe you need your own function or modification.
online_pages() does very similar. But, hmm,.. writing something open coded one
for crashkernel is not very bad, I think.