On Mon, Feb 07, 2022 at 09:57:55AM +0100, Jan Beulich wrote:
> On 06.02.2022 20:28, Julien Grall wrote:
> > From: Julien Grall <[email protected]>
> >
> > When using EFI, the VGA information is fetched using the EFI
> > boot services. However, Xen will have exited the boot services.
> > Therefore, we need to find a different way to pass the information
> > to dom0.
> >
> > For PV dom0, they are part of the start_info. But this is not
> > something that exists on Arm. So the best way would to be to
> > use a hypercall.
> >
> > For now the structure layout is based on dom0_vga_console_info
> > for convenience. I am open on another proposal.
> >
> > Signed-off-by: Julien Grall <[email protected]>
>
> Cc-ing Roger as this may want using for PVH Dom0 also on x86; my
> first attempt to propagate this information was rejected.
I think it's easier to use a Xen specific layout in XENPF, as that's
already a Xen specific interface.
I wonder however if passing the information here (instead of doing it
in the start info or equivalent) could cause a delay in the
initialization of the video console. I guess the same happens when
using the Xen consoles (either the hypercall one or the shared ring),
so it's fine.
> > --- a/xen/include/public/platform.h
> > +++ b/xen/include/public/platform.h
> > @@ -244,6 +244,7 @@ DEFINE_XEN_GUEST_HANDLE(xenpf_efi_runtime_call_t);
> > #define XEN_FW_EFI_PCI_ROM 5
> > #define XEN_FW_EFI_APPLE_PROPERTIES 6
> > #define XEN_FW_KBD_SHIFT_FLAGS 5
> > +#define XEN_FW_VGA_INFO 6
>
> Perhaps s/VGA/VIDEO/, despite ...
>
> > struct xenpf_firmware_info {
> > /* IN variables. */
> > uint32_t type;
> > @@ -311,6 +312,7 @@ struct xenpf_firmware_info {
> >
> > /* Int16, Fn02: Get keyboard shift flags. */
> > uint8_t kbd_shift_flags; /* XEN_FW_KBD_SHIFT_FLAGS */
> > + struct dom0_vga_console_info vga;
>
> ... the structure name including "vga" (but if the #define is adjusted,
> the field name would want to become "video" as well).
It's my understanding that this will forcefully be
XEN_VGATYPE_EFI_LFB, at which point we could consider giving a type
name to the vesa_lfb field of dom0_vga_console_info (video_lfb) and
use the same struct here?
There's no need to propagate XEN_VGATYPE_TEXT_MODE_3 into this
interface.
Thanks, Roger.
