https://github.com/torvalds/linux
Revision 83e68189745ad931c2afd45d8ee3303929233e7f authored by Matt Fleming on 14 November 2012, 09:42:35 UTC, committed by H. Peter Anvin on 30 January 2013, 19:51:59 UTC
Originally 'efi_enabled' indicated whether a kernel was booted from
EFI firmware. Over time its semantics have changed, and it now
indicates whether or not we are booted on an EFI machine with
bit-native firmware, e.g. 64-bit kernel with 64-bit firmware.
The immediate motivation for this patch is the bug report at,
https://bugs.launchpad.net/ubuntu-cdimage/+bug/1040557
which details how running a platform driver on an EFI machine that is
designed to run under BIOS can cause the machine to become
bricked. Also, the following report,
https://bugzilla.kernel.org/show_bug.cgi?id=47121
details how running said driver can also cause Machine Check
Exceptions. Drivers need a new means of detecting whether they're
running on an EFI machine, as sadly the expression,
if (!efi_enabled)
hasn't been a sufficient condition for quite some time.
Users actually want to query 'efi_enabled' for different reasons -
what they really want access to is the list of available EFI
facilities.
For instance, the x86 reboot code needs to know whether it can invoke
the ResetSystem() function provided by the EFI runtime services, while
the ACPI OSL code wants to know whether the EFI config tables were
mapped successfully. There are also checks in some of the platform
driver code to simply see if they're running on an EFI machine (which
would make it a bad idea to do BIOS-y things).
This patch is a prereq for the samsung-laptop fix patch.
Cc: David Airlie <airlied@linux.ie>
Cc: Corentin Chary <corentincj@iksaif.net>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Olof Johansson <olof@lixom.net>
Cc: Peter Jones <pjones@redhat.com>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: Steve Langasek <steve.langasek@canonical.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Konrad Rzeszutek Wilk <konrad@kernel.org>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: <stable@vger.kernel.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
1 parent f44310b
Tip revision: 83e68189745ad931c2afd45d8ee3303929233e7f authored by Matt Fleming on 14 November 2012, 09:42:35 UTC
efi: Make 'efi_enabled' a function to query EFI facilities
efi: Make 'efi_enabled' a function to query EFI facilities
Tip revision: 83e6818
README.AddingFirmware
DO NOT ADD FIRMWARE TO THIS DIRECTORY.
======================================
This directory is only here to contain firmware images extracted from old
device drivers which predate the common use of request_firmware().
As we update those drivers to use request_firmware() and keep a clean
separation between code and firmware, we put the extracted firmware
here.
This directory is _NOT_ for adding arbitrary new firmware images. The
place to add those is the separate linux-firmware repository:
git://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git
That repository contains all these firmware images which have been
extracted from older drivers, as well various new firmware images which
we were never permitted to include in a GPL'd work, but which we _have_
been permitted to redistribute under separate cover.
To submit firmware to that repository, please send either a git binary
diff or preferably a git pull request to:
David Woodhouse <dwmw2@infradead.org>
Ben Hutchings <ben@decadent.org.uk>
Your commit should include an update to the WHENCE file clearly
identifying the licence under which the firmware is available, and
that it is redistributable. If the licence is long and involved, it's
permitted to include it in a separate file and refer to it from the
WHENCE file.
Ideally, your commit should contain a Signed-Off-By: from someone
authoritative on the licensing of the firmware in question (i.e. from
within the company that owns the code).
Computing file changes ...
