Date: Wed, 2 Nov 2016 09:34:33 +0800
From: Baoquan He <bhe@redhat.com>
To: Dave Anderson <anderson@redhat.com>
Cc: Dave Young <dyoung@redhat.com>, kexec@lists.infradead.org,
        linux-kernel@vger.kernel.org, keescook@chromium.org,
        ats-kumagai@wm.jp.nec.com, thgarnie@google.com,
        takahiro akashi <takahiro.akashi@linaro.org>, mingo@redhat.com,
        ebiederm@xmission.com, hpa@zytor.com, tglx@linutronix.de,
        akpm@linux-foundation.org, tonli@redhat.com, panand@redhat.com
Subject: Re: [PATCH] kexec: Export memory sections virtual addresses to
 vmcoreinfo
Message-ID: <20161102013433.GA3928@x1>
References: <1475743561-23912-1-git-send-email-bhe@redhat.com>
 <20161101051019.GB4625@dhcp-128-65.nay.redhat.com>
 <20161101053353.GC20838@x1>
 <115590076.11735656.1478009614692.JavaMail.zimbra@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <115590076.11735656.1478009614692.JavaMail.zimbra@redhat.com>
User-Agent: Mutt/1.7.0 (2016-08-17)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1417
Lines: 39

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