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From: Alex =?utf-8?Q?Benn=C3=A9e?= <alex.bennee@linaro.org>
In-reply-to: <1465026847-6744-1-git-send-email-rth@twiddle.net>
Date: Mon, 30 Jan 2017 10:40:17 +0000
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Subject: Re: [Qemu-devel] [PATCH 0/2] tcg/i386 guest_base improvements
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To: Richard Henderson <rth@twiddle.net>
Cc: qemu-devel@nongnu.org


Richard Henderson <rth@twiddle.net> 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