Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

Path	csiph.com!eternal-september.org!feeder.eternal-september.org!news.unit0.net!news.panservice.it!bofh.it!news.nic.it!robomod
From	Dave Young <dyoung@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.
Date	Tue, 28 Jun 2016 21:30:02 +0200
Message-ID	<rP6RQ-2GD-17@gated-at.bofh.it> (permalink)
References	<rMzQl-1Gf-3@gated-at.bofh.it> <rNeTw-3z3-33@gated-at.bofh.it> <rOHA5-2Ez-27@gated-at.bofh.it> <rOHJM-2Ik-21@gated-at.bofh.it> <rOLkl-59s-11@gated-at.bofh.it>
MIME-Version	1.0
Content-Type	text/plain; charset=us-ascii
Content-Disposition	inline
User-Agent	Mutt/1.5.24 (2015-08-30)
X-Scanned-By	MIMEDefang 2.68 on 10.5.11.26
X-Greylist	Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Tue, 28 Jun 2016 19:21:07 +0000 (UTC)
Sender	robomod@news.nic.it
List-ID	<linux-kernel.vger.kernel.org>
X-Mailing-List	linux-kernel@vger.kernel.org
Approved	robomod@news.nic.it
Lines	46
Organization	linux.* mail to news gateway
X-Original-Cc	linuxppc-dev@lists.ozlabs.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, vgoyal@redhat.com, Eric Biederman <ebiederm@xmission.com>
X-Original-Date	Tue, 28 Jun 2016 15:20:55 -0400
X-Original-Message-ID	<20160628192055.GA3165@dhcp-128-65.nay.redhat.com>
X-Original-References	<1466538521-31216-1-git-send-email-bauerman@linux.vnet.ibm.com> <4923900.bfxGnX6mM2@hactar> <20160627161948.GA5876@dhcp-128-65.nay.redhat.com> <5428891.iJNV8CI1We@hactar> <20160627202125.GA9230@dhcp-128-65.nay.redhat.com>
X-Original-Sender	linux-kernel-owner@vger.kernel.org
Xref	csiph.com linux.kernel:1433231

Show key headers only | View raw

On 06/27/16 at 04:21pm, Dave Young wrote:
> Please ignore previous reply, I mistakenly send a broken mail without
> subject, sorry about it. Resend the reply here.
> 
> On 06/27/16 at 01:37pm, Thiago Jung Bauermann wrote:
> > Am Dienstag, 28 Juni 2016, 00:19:48 schrieb Dave Young:
> > > On 06/23/16 at 12:37pm, Thiago Jung Bauermann wrote:
> > > > Am Donnerstag, 23 Juni 2016, 01:44:07 schrieb Dave Young:
> > > > What is bad about the description of top_down?
> > > It is not clear enough to me, I personally think the original one in
> > > source code is better:
> > > /* allocate from top of memory hole */
> > 
> > Actually I realized there's some discrepancy in how the x86 code uses 
> > top_down and how I need it to work in powerpc. This may be what is confusing 
> > about my comment and the existing comment.
> > 
> > x86 always walks memory from bottom to top but if top_down is true, in each 
> > memory region it will allocate the memory hole in the highest address within 
> > that region. I don't know why it is done that way, though.
> 
> I think we did not meaning to do this, considering kdump we have only
> one crashkernel region for searching (crashk_res) so it is fine.
> For kexec maybe changing the walking function to accept top_down is
> reasonable.
>  
> Ccing Vivek see if he can remember something..
> 
> > 
> > On powerpc, the memory walk itself should be from top to bottom, as well as 
> > the memory hole allocation within each memory region.

What is the particular reason in powerpc for a mandatory top to bottom
walking?

> > 
> > Should I add a separate top_down argument to kexec_locate_mem_hole to 
> > control if the memory walk should be from top to bottom, and then the 
> > bottom_up member of struct kexec_buf controls where inside each memory 
> > region the memory hole will be allocated?

Using one argument for both sounds more reasonable than using a separate
argument for memory walk..

Thanks
Dave

Thread

Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from  kexec_add_buffer. Dave Young <dyoung@redhat.com> - 2016-06-27 18:30 +0200
  Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer. Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-06-27 18:40 +0200
    Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer. Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-06-27 19:00 +0200
    Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from  kexec_add_buffer. Dave Young <dyoung@redhat.com> - 2016-06-27 22:30 +0200
      Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from  kexec_add_buffer. Dave Young <dyoung@redhat.com> - 2016-06-28 21:30 +0200
        Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer. Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-06-29 00:20 +0200
          Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from  kexec_add_buffer. Dave Young <dyoung@redhat.com> - 2016-06-29 21:50 +0200
            Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer. Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-06-29 23:20 +0200
              Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from  kexec_add_buffer. Dave Young <dyoung@redhat.com> - 2016-06-30 17:50 +0200
                Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer. Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-06-30 19:40 +0200
                Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from  kexec_add_buffer. Dave Young <dyoung@redhat.com> - 2016-06-30 23:40 +0200

csiph-web