Re: [PATCH] kexec: Export memory sections virtual addresses to vmcoreinfo

From: Baoquan He
Date: Tue Nov 01 2016 - 21:34:41 EST

Hi Dave,

On 11/01/16 at 10:13am, Dave Anderson wrote:
> > > But we have this in mainline which also introduced the VMCOREINFO
> > > numbers, can you send a patch to revert them?
> >
> > OK, will do.
> >
> > However for find_vmemmap_x86_64() in makedumpfile, vmemmap_start is
> > still needed. I checked code, seems no better way to avoid. I am not
> > sure how many people are really using "-e" option to exclude unused
> > vmemmap pages.
> >
> > Maybe just leave it as is, and fix it when people complain?
> Speaking of complaints, is there any chance you can make the
> x86_64 "phys_base" value available? The VMCOREINFO_SYMBOL(phys_base)
> is useless since its contents are needed in order to access the
> symbol address.

Yeah, the current exporting of virt addr of phys_base is really useless
for x86_64. While I saw you have got phys_base from kdump-ed vmcore elf
program header since kexec-tools has created that pt_load for kernel text

machdep->machspec->phys_base = phdr->p_paddr - (phdr->p_vaddr & ~(__START_KERNEL_map));

Do you still want the value of phys_base? If yes, I can change it to
export the real value of phys_base, not &phys_base.

In fact, exporting &phys_base was done in 2008, makedumpfile has taken
the similar way you use in crash to get value of phys_base. Means it has
been ignored very earlier. You could be the first person to complain
about it.