Hi Dave,
Thank you for your comment.
On 10/22/2015 12:25 PM, Dave Young wrote:
Hi, AKASHI,
On 10/19/15 at 11:38pm, Geoff Levand wrote:
From: AKASHI Takahiro <[email protected]>
On crash dump kernel, all the information about primary kernel's core
image is available in elf core header specified by "elfcorehdr=" boot
parameter. reserve_elfcorehdr() will set aside the region to avoid any
corruption by crash dump kernel.
Crash dump kernel will access the system memory of primary kernel via
copy_oldmem_page(), which reads one page by ioremap'ing it since it does
not reside in linear mapping on crash dump kernel.
Please note that we should add "mem=X[MG]" boot parameter to limit the
memory size and avoid the following assertion at ioremap():
if (WARN_ON(pfn_valid(__phys_to_pfn(phys_addr))))
return NULL;
when accessing any pages beyond the usable memories of crash dump kernel.
How does kexec-tools pass usable memory ranges to kernel? using dtb?
Passing an extra mem=X sounds odd in the design. Kdump kernel should get
usable ranges and hanle the limit better than depending on an extern kernel
param.
Well, regarding "depending on an external kernel param,"
- this limitation ("mem=") is compatible with arm(32) implementation although
it is not clearly described in kernel's Documentation/kdump/kdump.txt.
- "elfcorehdr" kernel parameter is mandatory on x86 as well as on arm/arm64.
The parameter is explicitly generated and added by kexec-tools.
Do I miss your point?
Thanks,
-Takahiro AKASHI
Thanks
Dave
_______________________________________________
kexec mailing list
[email protected]
http://lists.infradead.org/mailman/listinfo/kexec
