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

Baoquan He
2016-11-02T13:48:32Z

On 11/02/16 at 09:29am, Dave Anderson wrote:
>
>
> ----- Original Message -----
> > 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
> > region.
> >
> > 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.
>
> No, this is not the first time it's been brought up. Anyway, yes,
> it would be preferable if it were readily available in vmcoreinfo
> rather than depending upon the PT_LOAD semantics.

All right, I need move KERNEL_IMAGE_SIZE to x86 64. Can change it in the
same patch. Will CC you when post.

Thanks
Baoquan