From: aflist2@gmail.com
To: qemu-devel@nongnu.org
Subject: [Qemu-devel] cirrus vga output corrupts on windows 98 after commit 2bec46dc97571a3c34b18fe4ca198e7bfbdca41f
Date: Mon, 10 Aug 2009 13:45:45 -0700 [thread overview]
Message-ID: <6c407d800908101345v46fe6e01ie3f3eb863e324852@mail.gmail.com> (raw)
hello,
when i run windows 98 with cirrus graphics, a corrupted version of the
boot graphic appears and the vm freezes. a picture of the screen is at
http://i31.tinypic.com/23sd5dd.jpg
according to git-bisect, this is the commit that breaks it:
http://git.savannah.gnu.org/cgit/qemu.git/commit/?id=2bec46dc97571a3c34b18fe4ca198e7bfbdca41f
vga optimization
Hypervisors like KVM perform badly while doing mmio on a loop, because
it'll generate an exit on each access. This is the case with VGA,
which results in very bad performance.
In this patch, we map the linear frame buffer as RAM, make sure it has
dirty region tracking enabled, and then just let the region to be
written.
notes:
* after this commit, it behaves as if i have less video ram. smaller
available modes, in less color depth. i have not found any software
that can display windows 98 detected video ram in 16 colors mode, so i
can't say how much the broken version finds. the working version
detects 4MB.
* qemu's window is resized to the correct resolution selected before
graphic corruption.
* i can reproduce this bug on latest git, 0.11.0-rc1, and 0.10.6.
0.9.1 is unaffected.
* anything greater than 640x480x16 colors freezes
reply other threads:[~2009-08-10 20:45 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
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=6c407d800908101345v46fe6e01ie3f3eb863e324852@mail.gmail.com \
--to=aflist2@gmail.com \
--cc=qemu-devel@nongnu.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).