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SubjectRe: [PATCH] x86/efi: Add EFI framebuffer earlyprintk support

* Peter Jones <pjones@redhat.com> wrote:

> On Thu, Oct 10, 2013 at 07:28:44PM +0200, Ingo Molnar wrote:
> >
> > Is a non-32-bit framebuffer a possibility? If yes then it might be nice to
> > emit an informative printk() here, so that users who try to enable EFI
> > early-printk can at least see why it's not working. (Assuming they get to
> > look at regular printk output, on a safe/working kernel.)
>
> Not really - the spec allows RGBx, BGRx, and for custom bit masks, but
> they're define like:
>
> typedef struct {
> UINT32 RedMask;
> UINT32 GreenMask;
> UINT32 BlueMask;
> UINT32 ReservedMask;
> } EFI_PIXEL_BITMASK;

Hm, that structure does not show up anywhere in the kernel that I can see.

How are those mask values to be interpreted? As regular bitmasks? Are bits
in the masks set to 1 consecutively, starting from bit 0?

Also, the main question would be, what is the typical value for
si->lfb_depth. 32 on almost all EFI systems? All around the map? Depends
on what graphics state the EFI bootloader passes us?

Thanks,

Ingo


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