Bug#996666: Xen PVH domains lack console

[Elliott Mitchell]

Package: grub-xen-host
Version: 2.04-20

I'm unsure which versions from stable were tried, but at a minimum
2.02+dfsg1-20+deb10u4 was and also had this issue.  I'm also unsure
whether this is actually a GRUB bug versus a Linux kernel bug.

When booting in x86 PVH mode the Linux kernel fails to load the Xen
virtual console as console.  As a result the kernel's dmesg is
unavailable for debugging during boot.

When using grub-x86_64-xen.bin (x86 PV mode) as Xen kernel:
$ cat /proc/consoles
tty0                 -WU (EC p  )    4:1
hvc0                 -W- (E  p  )  229:0
$ 

When using grub-i386-xen_pvh.bin (x86 PVH mode) as Xen kernel:
$ cat /proc/consoles
tty0                 -WU (EC p  )    4:1
$ 


When using Tianocore's XEN_EFI.fd (arm64 PVH mode) as Xen kernel:
$ cat /proc/consoles
hvc0                 -W- (EC p  )  229:0
$ 

Presently I think GRUB is more likely the culprit, but this is far from
certain.  Notably there are a few messages from the ACPI code, so I'm
wondering if GRUB sets up an ACPI table which isn't quite right.

I'm surprised at "tty0" being listed given the complete lack of any
sort of potential console device.  Yet this is x86, so I can understand.


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