Hi, AKASHI, On 10/19/15 at 11:38pm, Geoff Levand wrote: > From: AKASHI Takahiro <takahiro.akashi at linaro.org> > > 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. Thanks Dave
