On Wed, Feb 02, 2022 at 06:46:25AM -0800, Andrea Bolognani wrote: > On Wed, Feb 02, 2022 at 02:32:32PM +0000, Daniel P. Berrangé wrote: > > On Wed, Feb 02, 2022 at 06:29:32AM -0800, Andrea Bolognani wrote: > > > On Wed, Feb 02, 2022 at 12:44:44PM +0000, Daniel P. Berrangé wrote: > > > > Introduce support for > > > > > > > > <serial type='pty'> > > > > <target type='isa-debug'> > > > > <model type='isa-debugcon'/> > > > > </target> > > > > <address type='isa' iobase='0x402'/> > > > > </console> > > > > > > > > which is used as a way to receive debug messages from the > > > > firmware on x86 platforms. > > > > > > > > Note that the default port is 0x0xe9 since that's the original > > > > Bochs debug port. Thus for use with SeaBIOS/OVMF, the iobase > > > > port needs to be explicitly set to 0x402. > > > > > > The default is not set anywhere in the code, so I guess we're relying > > > on the fact that QEMU has that as the current default. Wouldn't it > > > make sense to have it reflected in the XML as well? > > > > > > The previous version used 0x402 as the default, which apparently > > > doesn't match QEMU's own but is what most people will want in > > > practice. Wouldn't that be a better default for us? People who care > > > about Bochs compatibility can always explicitly set the appropriate > > > value themselves. > > > > The previous bversion was a mistake because I incorrectly thought > > 402 was QEMU's own default. I also mistakenly thought we needed > > to set it explicitly for ABI compat, but that's not the case because > > the machine type ensures that. > > > > So preferrable to not override QEMU's own defaults in libvirt. > > I think it would still make sense to reflect QEMU's current default > in the XML, which would make sure that the same input XML results in > the same device even if QEMU decides to change its defaults later on. We don't do that for any existing ISA devices AFAICT, so I'm not finding a compelling reason to treat isa-debugcon as special. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
