Bug#617538: update-grub (mk-grubconfig) does not support old "xenkopt"

[Ian Jackson]

Package: grub-common
Version: 1.98+20100804-14

The grub 2 config generator does not appear to support an equivalent
to the "xenkopt" option from old (grub 1) update-grub.

This is used to provide kernel command line arguments that apply only
when booting the kernel under Xen.  For example, a pvops kernel which
can boot dom0 vs. baremetal, and where a serial console is in use,
would normally want
   kopt="console=ttyS0,115200,8n1"
   xenkopt="console=hvc0"
since when booting under Xen the kernel needs to use the Xen console
rather than direct access to the serial port.

I suggest adding two variables
  GRUB_CMDLINE_LINUX_XEN
  GRUB_CMDLINE_LINUX_XEN_DEFAULT
which when specified /override/ the values of
  GRUB_CMDLINE_LINUX
  GRUB_CMDLINE_LINUX_DEFAULT

Ian.