Question about crashkernel parameter on cmdline

[Li Haifeng]

Hi, list.

I am running kexec-tools on ARM soc to dump vmcore file. In my case,
the crashkernel parameter of crash kernel 's cmdline is
"crashkernel=20M at 10M". Then in bash of crash kernel, "echo c >
/proc/sysrq-trigger", and the capture kernel launches. But it will
fail on initializing /proc/vmcore. Because it trigger
"WARN_ON(pfn_valid(pfn))" in   __arm_ioremap_pfn_caller()
@arch/arm/mm/ioremap.c.

I check the reason as follows.

 #define pfn_valid(pfn) ((pfn) >= ARCH_PFN_OFFSET && ((pfn) -
ARCH_PFN_OFFSET) < max_mapnr)

To my case, pfn:x01d00, ARCH_PFN_OFFSET:0, max_mapnr:0x1300.
So pfn-ARCH_PFN_OFFSET is less than max_mapnr, and the
WARN_ON(pfn_valid(pfn)) is triggered on.

I want to know, to ignore this warning, whether I should comment this
WARN_ON() in kernel source code for my case.
And another doubt, will this warning corrupt my dumpfile? Because,
when I use the crash utility to analyse this vmcore, many errors
throw.

Any suggestion will be appreciate.

Thanks.