Messages in this thread | | | Date | Fri, 11 Apr 2014 08:44:28 +0100 | From | Matt Fleming <> | Subject | Re: "54b52d87268034859191d671505bb1cfce6bd74d - x86/efi: Build our own EFI services pointer table" breaks boot on thinkpad t440s |
| |
On Fri, 11 Apr, at 09:20:44AM, Ingo Molnar wrote: > > Might be prudent to do the same in __file_size32(), instead of > truncating silently, especially is that function too has a u64 output > AFAICS.
This change isn't required for __file_size32() because we only use that function if the firmware is 32-bit. The signature of EFI_FILE_PROTOCOL.GetInfo() looks like this,
EFI_STATUS (*EFI_FILE_GET_INFO) ( EFI_FILE_PROTOCOL *This, EFI_GUID *InformationType, UINTN *BufferSize, void *Buffer );
UINTN translates to unsigned long, so for 32-bit firmware is u32. The firmware will never write 64-bits to &info_sz in __file_size32().
> Also, while reviewing the file I noticed that there's "u32 fb_base", > which is recovered like: > > status = __gop_query64(gop64, &info, &size, &fb_base); > > but ->frame_buffer_base is u64. Is it always guaranteed u32?
Good catch. ->frame_buffer_base isn't always u32, but we only have u32 bits in which to store it (struct screen_info.lfb_base), so we implicitly truncate it,
static efi_status_t __gop_query64(struct efi_graphics_output_protocol_64 *gop64,
[...]
*fb_base = mode->frame_buffer_base;
But you raise a good point - it would probably make more sense to complain loudly if we get an address above 0xffffffff.
-- Matt Fleming, Intel Open Source Technology Center
| |