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Re: [Qemu-devel] [PATCH 0/2] tcg/i386 guest_base improvements
From: |
Alex Bennée |
Subject: |
Re: [Qemu-devel] [PATCH 0/2] tcg/i386 guest_base improvements |
Date: |
Mon, 30 Jan 2017 10:40:17 +0000 |
User-agent: |
mu4e 0.9.19; emacs 25.1.91.6 |
Richard Henderson <address@hidden> writes:
> The first change does two things: (1) improve bsd-user so that it
> doesn't continually reload guest_base into a temp register and
> (2) extract the bulk of the guest_base logic to a routine that
> is run once at startup.
>
> The second change adds segmentation support to 32-bit linux. There,
> if we're using a guest base, we can save 3 bytes per memory op by
> using a segment override. In addition, if we're using a reserved_va,
> we can set up the segment such that guest memory references are
> constrained by the segment.
>
> Comments?
I'm not sure how to best review this given its fairly low level
x86 stuff. Do you have any numbers to show how this improves things?
>
>
> r~
>
>
> Richard Henderson (2):
> tcg/i386: Reserve register for guest_base if a segment isn't available
> tcg/i386: Use segment for 32-bit guest base on linux
>
> tcg/i386/tcg-target.inc.c | 181
> +++++++++++++++++++++++++---------------------
> 1 file changed, 100 insertions(+), 81 deletions(-)
--
Alex Bennée
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