[SeaBIOS] S3 resume is broken on QEMU

[Alon Levy]

On Sun, Jan 22, 2012 at 12:46:43PM +0200, Gleb Natapov wrote:
> On Fri, Jan 20, 2012 at 04:23:15PM +0100, Gerd Hoffmann wrote:
> >   Hi,
> > 
> > >> I'm 99% sure that wont work.  Option roms have to be copied from PCI
> > > You 99% sure it wont work on real HW or on QEMU? IIRC QEMU puts vgabios
> > > into 0xc0000 directly.
> > 
> > That is looooooooooooooooong history, it went away about the same time
> > qemu switched from bochs bios to seabios.
> > 
> > These days seabios loads them from either pci rom bar or via fw_cfg.
> > 
> Ah yeah fw_cfg. How could I forget about it :) Still we know what our
> vgabios is doing so we can make sure it works. bochs bios had to be
> fixed to make S3 work too.
> 
> > > Windows is actually smart. It knows that it can support S3 resume on
> > > generic VGA so it does not allow you to do S3 suspend when one is in
> > > use. We managed to trick WindowsXP + cirrus to allow S3 suspend by DSDT
> > > magic, but after resume GUI is not usable. Still good enough for running
> > > WHQL. The only way S3 works on all Windowses is by using QXL device and
> > > driver that supports S3.
> > 
> > If you ask the linux graphics guys the situation is simliar on linux.
> Well it is obviously not :) Microsoft makes sure resume works if suspend
> is allowed.
> 
> > S3 without kms driver doesn't work reliably and isn't supported[1]. Only
> > difference is that linux doesn't enforce this by refusing to suspend
> > without kms.
> > 
> If it isn't supported it should not be allowed. Why Linux graphics guys
> do not send patch that disables S3 on unsupported configurations? Did
> this come up in [1]?
> 
> But I want to understand their support statement a little bit better. 
> Do you need kms driver for resume to be "supported" even if X is
> running? Because if X is not enough we may as well remove S3 from dsdt.
> 
> BTW does QXL have kms driver?

No. (== not yet.. I'm actually working on this)

> 
> > cheers,
> >   Gerd
> > 
> > [1] summary of a longish discussion, don't remember where though.
> 
> --
> 			Gleb.
> 
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