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RE: [Xen-devel] vesafb


  • To: "ron minnich" <rminnich@xxxxxxxxx>, "xen-devel" <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: "Ian Pratt" <Ian.Pratt@xxxxxxxxxxxx>
  • Date: Mon, 30 Apr 2007 22:52:05 +0100
  • Delivery-date: Mon, 30 Apr 2007 14:51:09 -0700
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AceLakBrQ8/x9YkET6SMoizMWGs4sgABUTrQ
  • Thread-topic: [Xen-devel] vesafb

> Can vesafb be used in a dom0? I ask because I can not get it to work.
> I am wondering if vm86mode is verboten in a xen guest.

Do you mean the linux kernel vesafb support?

This relies on Linux's very early bzImage real mode code to make the
call to the VESA BIOS to put the framebuffer in graphics mode. Since we
enter PV Linux in 32b mode straight from Xen there's no opportunity to
do this. vm86 mode is not involved.

VESA driver support in the Xserver should work just fine.

As regards enabling vesafb, it might be nice to add support to Xen to
drop into real mode via a trampoline in the bottom megabyte and execute
a BIOS call (marshalling the registers in each direction). We can then
get the dom0 kernel to make this hypercall when initialising the vesafb.


Ron, your BIOS experience would make you the ideal person to do this :-)


[There's code in syslinux that could be cribbed.]

Ian


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