[Bug 1341944] Re: 32-Bit UEFI bootloader support needed
carlix
1341944 at bugs.launchpad.net
Mon May 30 01:27:15 UTC 2016
Debian testing multiarch work out of the box
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https://bugs.launchpad.net/bugs/1341944
Title:
32-Bit UEFI bootloader support needed
Status in debian-installer:
New
Status in debian-installer package in Ubuntu:
Confirmed
Status in grub2 package in Ubuntu:
Triaged
Status in live-build package in Ubuntu:
Confirmed
Status in ubiquity package in Ubuntu:
Confirmed
Bug description:
As of now, Ubuntu and other major Linux distributions do not support
the use of a 32-bit EFI bootloader on UEFI machines. This has become
extremely problematic due to the popularity of Intel Atom-based
tablets and compact laptops. Atom-based devices are generally limited
in storage space (32GB or 64GB eMMC is common), and as a result these
devices almost universally ship with Windows 8.1 32-bit installed
(winsxs consumes a significant amount of storage space in order to
support 32-bit binaries in a 64-bit environment). By design, UEFI must
use the same architecture used by the bootloader.
While most modern computers indeed use a 64-bit UEFI implementation
due to the fact that new computers generally ship with a 64-bit
operating system (be it OS X or Windows 8.1), Atom-based devices do
*not* use a 64-bit operating system or UEFI implementation. This is by
design.
Intel released a new Atom iteration (Bay Trail) in late 2013 and has
indicated that they will continue to develop and release Atom CPUs due
to consumer market demand. At the time of this filing there are a
number of Atom-based tablets and compact laptops/netbooks being
actively sold and marketed by major OEMs including Dell, HP, ASUS, and
Acer. None of these devices have 64-bit UEFI firmware. It is also
important to note that these Atom CPUs are 64-bit, but explicitly
require a 32-bit UEFI bootloader.
The current Linux kernel in Ubuntu 14.04 does support booting the
64-bit signed kernel from a 32-bit Grub EFI bootloader. I can confirm
this on at least two 32-bit UEFI devices, the ASUS Transformer T100TA
and the Acer Aspire Switch 10. Unfortunately, the lack of official
32-bit EFI bootloader support in Ubuntu makes accomplishing this far
from trivial and beyond the capacity of many users new to Linux as an
alternative to Microsoft Windows.
This bug is currently marked as a security vulnerability due to the
fact that as of now, it is necessary to compile Grub2 32-bit EFI
manually in order to boot Linux. This negates the digital signature
check that allows keeping Secure Boot enabled on modern UEFI-based
machines.
Considering the above, it is very important to include a 32-bit UEFI
bootloader as an update to Grub2 in Trusty and all future releases of
Ubuntu.
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