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

From Baoquan He <bhe@redhat.com>
Newsgroups linux.kernel
Subject Re: [PATCH] kexec: Export memory sections virtual addresses to vmcoreinfo
Date 2016-11-02 02:40 +0100
Message-ID <sySH0-80X-5@gated-at.bofh.it> (permalink)
References <spdjI-6HB-41@gated-at.bofh.it> <syzEl-4g9-7@gated-at.bofh.it> <syzXH-4pJ-5@gated-at.bofh.it> <syI4V-1lE-9@gated-at.bofh.it>
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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.

Thanks
Baoquan

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Thread

Re: [PATCH] kexec: Export memory sections virtual addresses to  vmcoreinfo Dave Young <dyoung@redhat.com> - 2016-11-01 06:20 +0100
  Re: [PATCH] kexec: Export memory sections virtual addresses to  vmcoreinfo Baoquan He <bhe@redhat.com> - 2016-11-01 06:40 +0100
    Re: [PATCH] kexec: Export memory sections virtual addresses to  vmcoreinfo Dave Anderson <anderson@redhat.com> - 2016-11-01 15:20 +0100
      Re: [PATCH] kexec: Export memory sections virtual addresses to  vmcoreinfo Baoquan He <bhe@redhat.com> - 2016-11-02 02:40 +0100
        Re: [PATCH] kexec: Export memory sections virtual addresses to  vmcoreinfo Dave Anderson <anderson@redhat.com> - 2016-11-02 14:40 +0100
          Re: [PATCH] kexec: Export memory sections virtual addresses to  vmcoreinfo Baoquan He <bhe@redhat.com> - 2016-11-02 14:50 +0100

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