[Bug 1785033] Re: GRUB needs to support 64-bit efi linear frame buffer address

[Ivan Hu]

Test with Dell's machine on Xenial with the grub2 xenail-proposed, and update grub-efi-amd64
and grub-efi-amd64-signed packages
got the correct 64-bit efi linear frame buffer address

[    0.923498] efifb: probing for efifb
[    0.923506] efifb: framebuffer at 0x4000000000, using 8100k, total 8100k
[    0.923507] efifb: mode is 1920x1080x32, linelength=7680, pages=1
[    0.923507] efifb: scrolling: redraw
[    0.923508] efifb: Truecolor: size=8:8:8:8, shift=24:16:8:0


** Tags removed: verification-needed-xenial
** Tags added: verification-done-xenial

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https://bugs.launchpad.net/bugs/1785033

Title:
  GRUB needs to support 64-bit efi linear frame buffer address

Status in HWE Next:
  In Progress
Status in OEM Priority Project:
  Triaged
Status in grub2 package in Ubuntu:
  Fix Released
Status in grub2-signed package in Ubuntu:
  Fix Released
Status in grub2 source package in Trusty:
  New
Status in grub2-signed source package in Trusty:
  New
Status in grub2 source package in Xenial:
  Fix Committed
Status in grub2-signed source package in Xenial:
  Fix Committed
Status in grub2 source package in Bionic:
  Fix Released
Status in grub2-signed source package in Bionic:
  Fix Released
Status in grub2 source package in Cosmic:
  Fix Released
Status in grub2-signed source package in Cosmic:
  Fix Released

Bug description:
  [Rationale]
  More firmwares support above 4G mmio configureation and the EFI Graphics Output Protocol can return a 64-bit linear frame buffer address have been implemented in some firmware/BIOS. Grub2 currently only pass 32-bit framebuffer base to kernel. The Linux kernel has already added support to handle 64-bit linear framebuffer address in the efifb driver now. So GRUB2 should support 64-bit EFI linear frame buffer address.

  [Impact]
  Some machines block booting with firmware/bios implemented 64-bit EFI linear frame buffer address,due to Grub passing incorrect(only 32-bit) EFI linear frame buffer.

  [Test cases]

  Need Bios/Firmware support,
  1) Make sure the machine with the Bios implemented 64-bit EFI linear frame buffer address. some machine need to enable above 4G mmio on bios setup menu.
  2) Boot up.

  [Solution]
  A patch has been committed and accepted by maintainer
  http://git.savannah.gnu.org/cgit/grub.git/commit/?id=886edba8770ccbc3def0af2a7d6b346d00d0af2f

  [Regression Potential]
  Minimal, it's unlikely completing the whole framebuffer address will affect those which hasn't used above 32-bits framebuffer address.

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