From: Olof Johansson <olof@lixom•net>
To: Paul Mackerras <paulus@samba•org>
Cc: linuxppc-dev@ozlabs•org, Jon Tollefson <kniht@linux•vnet.ibm.com>,
Will Schmidt <will_schmidt@vnet•ibm.com>
Subject: Re: [PATCH] Use 1TB segments
Date: Tue, 2 Oct 2007 22:27:47 -0500 [thread overview]
Message-ID: <20071003032747.GA7822@lixom.net> (raw)
In-Reply-To: <18179.1934.821688.836972@cargo.ozlabs.ibm.com>
On Wed, Oct 03, 2007 at 01:07:58PM +1000, Paul Mackerras wrote:
> Olof Johansson writes:
>
> > > This makes the kernel use 1TB segments for all kernel mappings and for
> > > user addresses of 1TB and above, on machines which support them
> > > (currently POWER5+ and POWER6).
> >
> > PA6T supports them as well :)
>
> In the patch, we don't actually hard-code the CPU_FTR_1T_SEGMENT bit
> in the cputable entry for any processor; instead we look in the
> ibm,processor-segment-sizes property in the cpu node(s) in the device
> tree.
Yep, I see that. I just wanted to clarify it for the (future) commit
message.
> Do you want us to add the CPU_FTR_1T_SEGMENT bit to the
> cputable entry for the PA6T, or will your firmware gives the
> ibm,processor-segment-sizes property in the device tree?
Thanks, but we've already got the properties there so it just works.
> > Wouldn't it be possible to stick with 1TB segments for the low range
> > for 64-bit processes as well, and have them allocate their hugepages
> > at >1TB?
>
> You mean, forbid hugepages below 1TB? That would be a user-visible
> ABI change. There are linker scripts for generating executables whose
> text and/or data can go in hugepages, and I believe they put the
> text/data below 1TB.
Hm, good point. Bummer.
-Olof
next prev parent reply other threads:[~2007-10-03 3:23 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-08-01 2:04 [PATCH] Use 1TB segments Paul Mackerras
2007-08-02 20:41 ` Will Schmidt
2007-08-02 22:37 ` Benjamin Herrenschmidt
2007-08-02 23:56 ` Will Schmidt
2007-08-03 2:53 ` David Gibson
2007-08-06 22:23 ` Jon Tollefson
2007-08-10 3:53 ` Michael Neuling
2007-10-02 18:37 ` Will Schmidt
2007-10-03 2:11 ` Olof Johansson
2007-10-03 3:07 ` Paul Mackerras
2007-10-03 3:27 ` Olof Johansson [this message]
2007-10-03 3:13 ` Paul Mackerras
2007-10-03 14:22 ` Will Schmidt
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