On Thu, Oct 09, 2025 at 01:56:09AM +0000, Dr. David Alan Gilbert wrote: > * Gerd Hoffmann ([email protected]) wrote: > > Starting with the edk2-stable202508 tag OVMF (and ArmVirt too) have > > optional support for logging to a memory buffer. There is guest side > > support -- for example in linux kernels v6.17+ -- to read that buffer. > > But that might not helpful if your guest stops booting early enough that > > guest tooling can not be used yet. So host side support to read that > > log buffer is a useful thing to have. > > > > This patch implements both qmp and hmp monitor commands to read the > > firmware log. > > > > Signed-off-by: Gerd Hoffmann <[email protected]> > > I'm OK with that, but I wonder if it would be better to have a command > that wrote the buffer to a file rather than displaying it directly; I don't > think we normally have anything else which outputs that much raw guest > provided data directly. > I assume when it goes wrong you end up with random unprintable junk in > the buffer.
128 KB is on the high side, but is not terrible. Libvirt (arbitrarily) caps a QMP reply at 10 MB. Libvirt is going to want to send this on to the client app and will likely do that streaming in memory, so having it iin a file is not required from our POV. IIRC, some of the query-block command replies can get insanely huge when the qcow2 chain is very long. 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 :|
