On 10/2/25 3:38 PM, Roger Pau Monné wrote:
On Thu, Oct 02, 2025 at 11:37:36AM +0100, Andrew Cooper wrote:
On 02/10/2025 11:22 am, Roger Pau Monne wrote:
Reading from the E9 port if the emergency console is active should return
0xe9 according to the documentation from Bochs:
https://bochs.sourceforge.io/doc/docbook/user/bochsrc.html
See `port_e9_hack` section description.
Fix Xen so it also returns the port address. OSes can use it to detect
whether the emergency console is available or not.
Fixes: d1bd157fbc9b ("Big merge the HVM full-virtualisation abstractions.")
Signed-off-by: Roger Pau Monné<[email protected]>
Reviewed-by: Andrew Cooper<[email protected]>
That's been wrong for rather a long time. How did you find it?
I came across the documentation above and I didn't remember Xen
returning any value for reads, which sadly was indeed true.
This was because I had the intention to suggest Alejandro to (also?) use
the port 0xe9 hack for printing from XTF, which should work for both
Xen and QEMU.
CC-ing Oleksii as you've tagged this for 4.21.
I was told that bugfixes didn't need a release-ack until hard code
freeze, which is the 31st of October?
I meant until the start of the hard code freeze, which is on October 4.
So there is no need for a release-ack for this patch.
Thanks.
~ Oleksii
