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i386/linux: Add support for ext_lfb_base

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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 <arindam.nath@amd.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This commit is contained in:
Arindam Nath 2018-07-12 19:02:49 +05:30 • committed by Vincent Batts
parent 0abda83427
commit 8db0a305e4
2 changed files with 11 additions and 1 deletions
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6
grub-core/loader/i386/linux.c
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@ -309,6 +309,12 @@ 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;