On Fri, Nov 14, 2025 at 02:05:18PM +0000, Leigh Brown wrote:
Hi Daniel, On 2025-11-14 12:48, Daniel P. Berrangé wrote:
On Fri, Nov 14, 2025 at 08:58:11AM +0000, Leigh Brown wrote: [...]
--- libvirt-11.3.0.orig/src/qemu/qemu_validate.c +++ libvirt-11.3.0/src/qemu/qemu_validate.c @@ -1304,15 +1304,7 @@ qemuValidateDomainDef(const virDomainDef /* On x86 -machine graphics=off toggles the use of the * serial console in SeaBIOS (and theoretically other * firmwares). - * On non-x86, it has also sorts of other effects - * on QEMU device models created and so we don't - * want to allow its use. */ - if (!ARCH_IS_X86(def->os.arch)) { - virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", - _("BIOS serial console only supported on x86 architectures")); - return -1; - } if (!def->nserials) { virReportError(VIR_ERR_XML_ERROR, "%s", _("need at least one serial port to use BIOS serial output"));
With that change, I can now create VMs with a serial console through virt-install on the Raspberry PI 5.
Have I got this right? If so, I'm happy to submit the patch.
This code is specifically only about a config setting for enabling the BIOS to output its boot message/menus on the serial console. It is independent of the broader serial console concept - a guest OS can still be configured with a serial console without the above change.
Sorry I wasn't 100% clear. With the change I am also able to use serial for the BIOS[1] and Grub[2]. Although the grub output is not quite right it works well enough to select an entry.
So the above code you're removing is related to the XML config <bios useserial='yes' /> This was originally added for SeaBIOS since it needed an explicit opt-in for using serial output, via the side-loaded sgabios. Recent SeaBIOS no longer needs sgabios, so useserial is obsolete. For non-x86, or x86 with EFI, we have no control knobs. Either the firmware used will output to the serial console or it won't, so the 'useserial=yes' config serves no purpose, which is why the above code rejects it. IOW, if you delete 'useserial=yes' from your guest XML it should all still work fine AFAIR With 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 :|