[PATCH] i386/linux: add support for ext_lfb_base (v2)

[Arindam Nath]

From: Arindam Nath <address@hidden>

v2: changes suggested by Daniel

  - added #if defined (GRUB_MACHINE_EFI) && defined (__x86_64__)
  - moved constant definitions to the beginning of header file

v1:

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 |  4 ++++
 include/grub/i386/linux.h     | 12 +++++++++++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/grub-core/loader/i386/linux.c b/grub-core/loader/i386/linux.c
index 083f9417c..246945abe 100644
--- a/grub-core/loader/i386/linux.c
+++ b/grub-core/loader/i386/linux.c
@@ -306,6 +306,10 @@ grub_linux_setup_video (struct linux_kernel_params *params)
   params->lfb_line_len = mode_info.pitch;
 
   params->lfb_base = (grub_size_t) framebuffer;
+#if defined (GRUB_MACHINE_EFI) && defined (__x86_64__)
+  params->ext_lfb_base = (grub_size_t) (((grub_uint64_t)(grub_size_t) 
framebuffer) >> 32);
+  params->capabilities |= VIDEO_CAPABILITY_64BIT_BASE;
+#endif
   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..04d277b4e 100644
--- a/include/grub/i386/linux.h
+++ b/include/grub/i386/linux.h
@@ -43,6 +43,13 @@
 
 #define GRUB_LINUX_CL_MAGIC            0xA33F
 
+#if defined (GRUB_MACHINE_EFI) && defined (__x86_64__)
+
+#define VIDEO_CAPABILITY_SKIP_QUIRKS   (1 << 0)
+#define VIDEO_CAPABILITY_64BIT_BASE    (1 << 1)        /* Frame buffer base is 
64-bit */
+
+#endif
+
 #ifdef __x86_64__
 
 #define GRUB_LINUX_EFI_SIGNATURE       \
@@ -188,8 +195,11 @@ struct linux_kernel_params
   grub_uint16_t lfb_pages;             /* 32 */
   grub_uint16_t vesa_attrib;           /* 34 */
   grub_uint32_t capabilities;          /* 36 */
+#if defined (GRUB_MACHINE_EFI) && defined (__x86_64__)
+  grub_uint32_t ext_lfb_base;          /* 3a */
+#endif
 
-  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