From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Hollis Blanchard <hollisb@us.ibm.com>
Cc: linuxppc-dev@ozlabs.org
Subject: Re: [RFC][PATCH] initial port of fixmap over from x86 for ppc32
Date: Fri, 04 Apr 2008 08:45:47 +1100 [thread overview]
Message-ID: <1207259147.10388.332.camel@pasglop> (raw)
In-Reply-To: <200804031347.54517.hollisb@us.ibm.com>
On Thu, 2008-04-03 at 13:47 -0500, Hollis Blanchard wrote:
>
> x86 virtualization implementations often needs a trampoline that's
> mapped into
> both host and guest virtual address space, so that's part of what
> you're
> seeing.
>
> In general though, it can be very useful for the host to own a piece
> of the
> guest's virtual address space. For example, the host could rewrite
> problematic guest instructions to branch to host-optimized code which
> avoids
> hypercalls. However, this is impossible unless the host knows it can
> overwrite some portion of the guest's effective address space.
>
> reserve_top_address() doesn't look complicated, so we might as well
> keep it ?
Agreed. In fact, using the top of the address space for that is a good
idea as you can do the branching there using absolute branch
instructions which is simpler.
Ben.
next prev parent reply other threads:[~2008-04-03 21:46 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-03 6:52 [RFC][PATCH] initial port of fixmap over from x86 for ppc32 Kumar Gala
2008-04-03 18:47 ` Hollis Blanchard
2008-04-03 21:45 ` Benjamin Herrenschmidt [this message]
2008-04-06 23:48 ` Paul Mackerras
2008-04-07 0:43 ` Benjamin Herrenschmidt
2008-04-07 13:09 ` Kumar Gala
2008-04-07 16:20 ` Scott Wood
2008-04-07 21:36 ` Kumar Gala
2008-04-07 23:51 ` Benjamin Herrenschmidt
2008-04-08 14:28 ` Kumar Gala
2008-04-08 16:24 ` Scott Wood
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=1207259147.10388.332.camel@pasglop \
--to=benh@kernel.crashing.org \
--cc=hollisb@us.ibm.com \
--cc=linuxppc-dev@ozlabs.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
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;
as well as URLs for NNTP newsgroup(s).