[PATCH] i386/linux: add support for ext_lfb_base

[Arindam Nath]

The EFI Graphics Output Protocol can return a 64-bit
linear frame buffer address in some firmware/BIOS
implementations. We currently only store the lower
32-bits in the lfb_base. This will eventually be
passed to Linux kernel and the efifb driver will
incorrectly interpret the framebuffer address as
32-bit address.

The Linux kernel has already added support to handle
64-bit linear framebuffer address in the efifb driver
since quite some time now.

This patch adds the support for 64-bit linear frame
buffer address in GRUB to address the above mentioned
scenario.

Signed-off-by: Arindam Nath <address@hidden>
---
 grub-core/loader/i386/linux.c | 2 ++
 include/grub/i386/linux.h     | 5 ++++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/grub-core/loader/i386/linux.c b/grub-core/loader/i386/linux.c
index 083f9417c..1644e8132 100644
--- a/grub-core/loader/i386/linux.c
+++ b/grub-core/loader/i386/linux.c
@@ -306,6 +306,8 @@ grub_linux_setup_video (struct linux_kernel_params *params)
   params->lfb_line_len = mode_info.pitch;
 
   params->lfb_base = (grub_size_t) framebuffer;
+  params->ext_lfb_base = (grub_size_t) (((grub_uint64_t)(grub_size_t) 
framebuffer) >> 32);
+  params->capabilities |= VIDEO_CAPABILITY_64BIT_BASE;
   params->lfb_size = ALIGN_UP (params->lfb_line_len * params->lfb_height, 
65536);
 
   params->red_mask_size = mode_info.red_mask_size;
diff --git a/include/grub/i386/linux.h b/include/grub/i386/linux.h
index da0ca3b83..e3f91e7c0 100644
--- a/include/grub/i386/linux.h
+++ b/include/grub/i386/linux.h
@@ -188,8 +188,11 @@ struct linux_kernel_params
   grub_uint16_t lfb_pages;             /* 32 */
   grub_uint16_t vesa_attrib;           /* 34 */
   grub_uint32_t capabilities;          /* 36 */
+#define VIDEO_CAPABILITY_SKIP_QUIRKS   (1 << 0)
+#define VIDEO_CAPABILITY_64BIT_BASE    (1 << 1)        /* Frame buffer base is 
64-bit */
+  grub_uint32_t ext_lfb_base;          /* 3a */
 
-  grub_uint8_t padding3[0x40 - 0x3a];
+  grub_uint8_t padding3[0x40 - 0x3e];
 
   grub_uint16_t apm_version;           /* 40 */
   grub_uint16_t apm_code_segment;      /* 42 */
-- 
2.17.1