From: "Cohen, Eugene" <eugene@xxxxxx>
The UEFI Specification permits Graphics Output Protocol (GOP) instances
without direct framebuffer access. This is indicated in the Mode structure
with a PixelFormat enumeration value of PIXEL_BLT_ONLY. Given that the
kernel does not know how to drive a Blt() only framebuffer (which is only
permitted before ExitBootServices() anyway), we should disregard such
framebuffers when looking for a GOP instance that is suitable for use as
the boot console.
So modify the EFI GOP initialization to not use a PIXEL_BLT_ONLY instance,
preventing attempts later in boot to use an invalid screen_info.lfb_base
address.
Fixes: 9822504c1fa5 ("efifb: Enable the efi-framebuffer platform driver ...")
Signed-off-by: Eugene Cohen <eugene@xxxxxx>
[ardb: - move Blt() only check into the loop
- clarify that Blt() only GOPs are unusable by the kernel]
Cc: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v4.7+
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
drivers/firmware/efi/libstub/gop.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/firmware/efi/libstub/gop.c b/drivers/firmware/efi/libstub/gop.c
index 932742e4cf23..24c461dea7af 100644
--- a/drivers/firmware/efi/libstub/gop.c
+++ b/drivers/firmware/efi/libstub/gop.c
@@ -149,7 +149,8 @@ setup_gop32(efi_system_table_t *sys_table_arg, struct screen_info *si,
status = __gop_query32(sys_table_arg, gop32, &info, &size,
¤t_fb_base);
- if (status == EFI_SUCCESS && (!first_gop || conout_found)) {
+ if (status == EFI_SUCCESS && (!first_gop || conout_found) &&
+ info->pixel_format != PIXEL_BLT_ONLY) {
/*
* Systems that use the UEFI Console Splitter may
* provide multiple GOP devices, not all of which are
@@ -266,7 +267,8 @@ setup_gop64(efi_system_table_t *sys_table_arg, struct screen_info *si,
status = __gop_query64(sys_table_arg, gop64, &info, &size,
¤t_fb_base);
- if (status == EFI_SUCCESS && (!first_gop || conout_found)) {
+ if (status == EFI_SUCCESS && (!first_gop || conout_found) &&
+ info->pixel_format != PIXEL_BLT_ONLY) {
/*
* Systems that use the UEFI Console Splitter may
* provide multiple GOP devices, not all of which are
--
2.9.3
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