[SeaBIOS] Re: [Qemu-devel] Regression with floppy drive controller

[Kevin O'Connor]

On Wed, Aug 21, 2019 at 08:42:08AM +0200, Gerd Hoffmann wrote:
> Hi,
> > Using the default QEMU config, we build SeaBIOS to use the TSC timer:
> >
> > builds/seabios-128k/.config:CONFIG_TSC_TIMER=y
> > builds/seabios-256k/.config:CONFIG_TSC_TIMER=y
> > Do we need a cpu with TSC support to run SeaBIOS?
>
> Hmm.  seabios uses pmtimer if available.  isapc has no pmtimer though,
> so it uses TSC instead.

But, SeaBIOS should have automatically detected no TSC and then fallen
back to the PIT.  And the check does work correctly with "-cpu 486" in
my tests.

Is the PIT not working for some reason in the original setup?  (Any
time I attempt to run with "-M isapc" I just get an "Unable to unlock
ram - bridge not found" error.)  The PIT seems to work okay in my
setup.

-Kevin