From: olof@lixom•net (Olof Johansson)
To: Mohan Kumar M <mohan@in•ibm.com>
Cc: Milton Miller II <miltonm@us•ibm.com>,
kexec@lists•infradead.org, linuxppc-dev@ozlabs•org,
Paul Mackerras <paulus@samba•org>,
ellerman@au1•ibm.com
Subject: Re: [Patch 2/2] Kexec/Kdump support - POWER6
Date: Thu, 24 May 2007 09:21:33 -0500 [thread overview]
Message-ID: <20070524142133.GA13191@lixom.net> (raw)
In-Reply-To: <20070524121751.GB4547@in.ibm.com>
On Thu, May 24, 2007 at 05:47:51PM +0530, Mohan Kumar M wrote:
> On Wed, May 23, 2007 at 08:55:00PM +1000, Paul Mackerras wrote:
> > Sachin P. Sant writes:
> >
> > > On Power machines supporting VRMA, Kexec/Kdump does not work.
> > > Hypervisor stores VRMA mapping used by the OS, in the hpte hash
> > > tables. Make sure these hpte entries are left untouched.
> >
> > Surely all we need to do is to avoid clearing the VRMA entries. We
> > can do this by not clearing any HPTE where the top 40 bits of the
> > first dword are 0x4001ffffff (B=1 for a 1TB segment and the
> > 0x0001ffffff special VSID). In fact we can avoid having to read each
> > entry by doing the H_REMOVEs with H_ANDCOND and the bolted bit when we
> > clear the hash table, and only reading the HPTEs for which the
> > H_REMOVE returns an error.
>
> So I tried 0x4000000000000000 as AVPN parameter and using that it
> removes all hpte entries other than VRMA(ie non 1TB segment size PTE
> entries).
>
> Tested on POWER6/POWER5 machines.
Hi,
As Paul says above, you need to check for failures and compare the VSID
and possibly unhash it anyway in case of non-match. Otherwise if the
kernel ever starts using 1TB segments for regular use, those pages will
never be unhashed. I don't see your code doing that now.
-Olof
next prev parent reply other threads:[~2007-05-24 14:17 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-22 12:22 [Patch 0/2] Kexec/Kdump support POWER6 Sachin P. Sant
2007-05-22 12:24 ` [Patch 1/2] " Sachin P. Sant
2007-05-22 12:26 ` [Patch 2/2] " Sachin P. Sant
2007-05-22 15:34 ` Olof Johansson
2007-05-23 5:13 ` Sachin P. Sant
2007-05-23 5:14 ` Sachin P. Sant
2007-05-23 9:37 ` [Patch 2/2] Kexec/Kdump support - POWER6 Sachin P. Sant
2007-05-23 10:55 ` Paul Mackerras
2007-05-24 12:17 ` Mohan Kumar M
2007-05-24 14:21 ` Olof Johansson [this message]
2007-05-25 8:55 ` [Patch ] " Sachin P. Sant
2007-05-25 22:43 ` Benjamin Herrenschmidt
2007-05-28 11:40 ` Sachin P. Sant
2007-05-28 21:31 ` Benjamin Herrenschmidt
2007-05-29 6:18 ` Sachin P. Sant
2007-05-29 6:58 ` Benjamin Herrenschmidt
2007-05-29 10:14 ` Michael Ellerman
2007-05-29 11:06 ` Stephen Rothwell
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20070524142133.GA13191@lixom.net \
--to=olof@lixom$(echo .)net \
--cc=ellerman@au1$(echo .)ibm.com \
--cc=kexec@lists$(echo .)infradead.org \
--cc=linuxppc-dev@ozlabs$(echo .)org \
--cc=miltonm@us$(echo .)ibm.com \
--cc=mohan@in$(echo .)ibm.com \
--cc=paulus@samba$(echo .)org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox