x86/boot: Clarify what x86_legacy_features.reserve_bios_regions does

It doesn't just control probing for the EBDA -- it controls whether we
detect and reserve the <1MB BIOS regions in general.

Signed-off-by: Andy Lutomirski <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Luis R. Rodriguez <[email protected]>
Cc: Mario Limonciello <[email protected]>
Cc: Matthew Garrett <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Toshi Kani <[email protected]>
Link: http://lkml.kernel.org/r/55bd591115498440d461857a7b64f349a5d911f3.1469135598.git.luto@kernel.org
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
index c519c052700a705b581c6f9a48576d5172c91267..66c15a01667f66dc6095914bb96c9f092a56127d 100644 (file)
--- a/arch/x86/include/asm/x86_init.h
+++ b/arch/x86/include/asm/x86_init.h
@@ -168,8 +168,9 @@ struct x86_legacy_devices {
  * struct x86_legacy_features - legacy x86 features
  *
  * @rtc: this device has a CMOS real-time clock present
- * @reserve_bios_regions: it's safe to search for the EBDA signature in the hardware's
- *     low RAM
+ * @reserve_bios_regions: boot code will search for the EBDA address and the
+ *     start of the 640k - 1M BIOS region.  If false, the platform must
+ *     ensure that its memory map correctly reserves sub-1MB regions as needed.
  * @devices: legacy x86 devices, refer to struct x86_legacy_devices
  *     documentation for further details.
  */