[Xen-devel] [PATCH 1/2] x86/ACPI: Parse ACPI_FADT_LEGACY_DEVICES

[Anshuman Gupta <anshuman.gupta@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx>]

From: "Luis R. Rodriguez" <mcgrof@xxxxxxxxxx>

ACPI 5.2.9.3 IA-PC Boot Architecture flag ACPI_FADT_LEGACY_DEVICES
can be used to determine if a system has legacy devices LPC or
ISA devices. The x86 platform already has a struct which lists
known associated legacy devices, we start off careful only
by disabling root devices we should not regress with. The struct
and device list can be expanded with time to cover more root
legacy components.

Change-Id: I85ba7dfb405c7faefc0f8e6b43a6e7260a27a1c9
Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: andrew.cooper3@xxxxxxxxxx
Cc: andriy.shevchenko@xxxxxxxxxxxxxxx
Cc: bigeasy@xxxxxxxxxxxxx
Cc: boris.ostrovsky@xxxxxxxxxx
Cc: david.vrabel@xxxxxxxxxx
Cc: ffainelli@xxxxxxxxxx
Cc: george.dunlap@xxxxxxxxxx
Cc: glin@xxxxxxxx
Cc: jgross@xxxxxxxx
Cc: jlee@xxxxxxxx
Cc: josh@xxxxxxxxxxxxxxxx
Cc: julien.grall@xxxxxxxxxx
Cc: konrad.wilk@xxxxxxxxxx
Cc: kozerkov@xxxxxxxxxxxxx
Cc: lenb@xxxxxxxxxx
Cc: lguest@xxxxxxxxxxxxxxxx
Cc: linux-acpi@xxxxxxxxxxxxxxx
Cc: lv.zheng@xxxxxxxxx
Cc: matt@xxxxxxxxxxxxxxxxxxx
Cc: mbizon@xxxxxxxxxx
Cc: rjw@xxxxxxxxxxxxx
Cc: robert.moore@xxxxxxxxx
Cc: rusty@xxxxxxxxxxxxxxx
Cc: tiwai@xxxxxxx
Cc: toshi.kani@xxxxxx
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Link: 
http://lkml.kernel.org/r/1460592286-300-13-git-send-email-mcgrof@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/kernel/acpi/boot.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 8816102..7a25121 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -936,6 +936,10 @@ late_initcall(hpet_insert_resource);
 
 static int __init acpi_parse_fadt(struct acpi_table_header *table)
 {
+       if (!(acpi_gbl_FADT.boot_flags & ACPI_FADT_LEGACY_DEVICES)) {
+               pr_debug("ACPI: no legacy devices present\n");
+               x86_platform.legacy.devices.pnpbios = 0;
+       }
 
        if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
            !(acpi_gbl_FADT.boot_flags & ACPI_FADT_8042) &&
-- 
2.7.4


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