Re: [PATCH] kdump, x86: report actual value of phys_base in VMCOREINFO

[HATAYAMA, Daisuke]

(2014/11/13 17:06), Petr Tesarik wrote:
> On Thu, 13 Nov 2014 09:17:09 +0900 (JST)
> HATAYAMA Daisuke <d.hatayama@xxxxxxxxxxxxxx> wrote:
>
> > From: Vivek Goyal <vgoyal@xxxxxxxxxx>
> > Subject: Re: [PATCH] kdump, x86: report actual value of phys_base in VMCOREINFO
> > Date: Wed, 12 Nov 2014 17:12:05 -0500
> >
> > > On Wed, Nov 12, 2014 at 03:40:42PM +0900, HATAYAMA Daisuke wrote:
> > > > Currently, VMCOREINFO note information reports the virtual address of
> > > > phys_base that is assigned to symbol phys_base. But this doesn't make
> > > > sense because to refer to value of the phys_base, it's necessary to
> > > > get the value of phys_base itself we are now about to refer to.
> > >
> > > Hi Hatayama,
> > >
> > > /proc/vmcore ELF headers have virtual address information and using
> > > that you should be able to read actual value of phys_base. gdb deals
> > > with virtual addresses all the time and can read value of any symbol
> > > using those headers.
> > >
> > > So I am not sure what's the need for exporting actual value of
> > > phys_base.
> >
> > Sorry, my logic in the patch description was wrong. For /proc/vmcore,
> > there's enough information for makedumpdile to get phys_base. It's
> > correct. The problem here is that other crash dump mechanisms that run
> > outside Linux kernel independently don't have information to get
> > phys_base.
>
> Yes, but these mechanisms won't be able to read VMCOREINFO either, will
> they?

I don't intend such sophisticated function only by VMCOREINFO.
Search vmcore for VMCOREINFO using strings + grep before opening it by crash.
I intend that only here.

--
Thanks.
HATAYAMA, Daisuke

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