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| From: | Paolo Bonzini |
| Subject: | Re: [Qemu-devel] [Qemu-ppc] qemu-system-ppc video artifacts since "tcg: drop global lock during TCG code execution" |
| Date: | Thu, 16 Mar 2017 07:39:43 +0100 |
| User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 |
On 14/03/2017 18:34, BALATON Zoltan wrote:
> Like from the display controller models that use
> memory_region_get_dirty() to check if the frambuffer needs to be
> updated? But all display adaptors seem to do this and the problem was
> only seem on ppc so it may be related to something ppc specific.
You need to use test_and_clear_dirty instead of get_dirty/reset_dirty.
Or alternatively you need to reset immediately after get_dirty. At
least cg3.c is doing
read dirty bitmap
read VRAM
clear dirty bitmap
which has a race.
Paolo
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