linux-kernel - Re: [PATCH 3/5 v4] Export memory_sysdev

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Date:	Thu, 22 Oct 2009 08:56:46 -0700
From:	Dave Hansen <dave@...ux.vnet.ibm.com>
To:	Nathan Fontenot <nfont@...tin.ibm.com>
Cc:	linuxppc-dev@...abs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/5 v4] Export memory_sysdev_class

On Thu, 2009-10-22 at 10:31 -0500, Nathan Fontenot wrote:
> Dave Hansen wrote:
> > On Wed, 2009-10-21 at 09:44 -0500, Nathan Fontenot wrote:
> >> Export the memory_sysdev_class structure.  This is needed so we can create
> >> a 'release' file in sysfs in addition to the existing 'probe' file in
> >> order to support DLPAR removal of memory on the powerpc/pseries platform.
> >> The new 'release' file will be powerpc/pseries only.
> > 
> > Please do it in generic code.  You may only need it on ppc today, but
> > somebody else is going to want the same thing tomorrow on another arch.
> 
> I thought about this but wasn't sure if having the probe/release sysfs files
> for memory and cpu be in generic code would be accepted.

Although we don't want to pollute the generic code with lots of per-arch
cruft, this still looks pretty generic to me.  It is also really nice to
have all of the sysfs files for one directory be in a single place in
the source.

> Would it be acceptable to put the new release file for memory under the
> ARCH_MEMORY_PROBE config option?

That sounds fine to me.  It may need a slightly tuned name if you can
think of anything better.  I can't off the top of my head.

x86's is really only there for testing reasons.   I would use mem= to
shrink a machine's memory at boot then use the probe file to re-add it
later.  I did that before I had hardware that could do real hotplug.

> This would reduce the number of arch'es
> that would require stubs as it appears only powerpc and x86 define this.

Yeah, that'd be a nice side-effect I guess.

-- Dave

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