Jeremy Fitzhardinge wrote:

If we're running under Xen, then there's no VT console.  This results
in vc->vc_screenbuf_size == 0, which causes alloc_bootmem to panic.
Don't bother allocating a vc_screenbuf if its going to be 0 sized.

NAK.

The *real* problem is that the real-mode boot code never ever runs, thus
SCREEN_INFO is not initialized (all zeros), and vgacon doesn't catch
that case.  Instead it thinks it runs on a EGA card with 0 lines and 0
columns.

So better fix vgacon to catch this and switch to the 80x25 dummy console
instead, patch attached.

cheers,

  Gerd