cirrus-vga is not properly reset

cirrus-vga is not properly reset

[Jan Kiszka]

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Hi,

when rebooting from non-text mode, the text output of BIOS and
bootloader is unreadable. This only happens with cirrus and the KVM
tree, std-vga is fine, cirrus with upstream QEMU is fine, too. Moreover,
-no-kvm makes no difference.

What's very strange about this: CirrusVGAState does not differ after
issuing a reset from text mode compared to a reset from graphic mode
(except for a needless re-init of some io_memory slots - will post a
cleanup patch upstream). Currently I have no clue where to look next.

Jan


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Re: cirrus-vga is not properly reset

[Jan Kiszka]

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Jan Kiszka wrote:
> Hi,
> 
> when rebooting from non-text mode, the text output of BIOS and
> bootloader is unreadable. This only happens with cirrus and the KVM
> tree, std-vga is fine, cirrus with upstream QEMU is fine, too. Moreover,
> -no-kvm makes no difference.

Looked at it again, and I was able to reproduce this problem with latest
QEMU, too. It just doesn't trigger that reliably as with kvm-userspace.

So I bet it has something to do with recent QEMU reset changes for vga
and cirrus (the display changes are not yet merged into kvm, so they
can't contribute to the reason). Moreover, the error pattern suggests
that correct text is written to the VGA RAM and attempted to dump to the
screen, but the font that should have been written to VGA RAM by the
BIOS is corrupted.

> 
> What's very strange about this: CirrusVGAState does not differ after
> issuing a reset from text mode compared to a reset from graphic mode
> (except for a needless re-init of some io_memory slots - will post a
> cleanup patch upstream). Currently I have no clue where to look next.
> 
> Jan
> 

Jan


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