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authorMatt Fleming <matt.fleming@intel.com>2012-11-14 09:42:35 +0000
committerBen Hutchings <ben@decadent.org.uk>2013-02-06 04:33:50 +0000
commit06c73e442edec7cda81193276c72fda1abb96fb0 (patch)
treee36e3634e266162ce46a9a921d7793fac2a58495 /drivers/acpi
parentbbc7d09f4a8680fa6ae6531048214f498b0562d2 (diff)
efi: Make 'efi_enabled' a function to query EFI facilities
commit 83e68189745ad931c2afd45d8ee3303929233e7f upstream. 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> Signed-off-by: Matt Fleming <matt.fleming@intel.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> [bwh: Backported to 3.2: - Adjust context (a lot) - Add efi_is_native() function from commit 5189c2a7c776 ('x86: efi: Turn off efi_enabled after setup on mixed fw/kernel') - Make efi_init() bail out when booted non-native, as it would previously not be called in this case - Drop inapplicable changes to start_kernel()] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'drivers/acpi')
-rw-r--r--drivers/acpi/osl.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index f31c5c5f1b7..a6664d21bc7 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -255,7 +255,7 @@ acpi_physical_address __init acpi_os_get_root_pointer(void)
return acpi_rsdp;
#endif
- if (efi_enabled) {
+ if (efi_enabled(EFI_CONFIG_TABLES)) {
if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
return efi.acpi20;
else if (efi.acpi != EFI_INVALID_TABLE_ADDR)