linux-kernel - [PATCH] ACPI / tables: Add acpi_force_32bit_fadt_addr option to force 32 bit FADT addresses

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Date:	Thu, 21 Jan 2016 17:05:47 +0000
From:	Colin King <colin.king@...onical.com>
To:	Jonathan Corbet <corbet@....net>,
	"Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
	linux-doc@...r.kernel.org, linux-acpi@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH] ACPI / tables: Add acpi_force_32bit_fadt_addr option to force 32 bit FADT addresses

From: Colin Ian King <colin.king@...onical.com>

BugLink: https://bugs.launchpad.net/bugs/1529381

Some HP laptops seem to have invalid 64 bit FADT X_PM* addresses
which are causing various boot issues.  In these cases, it would
be useful to force ACPI to use the valid legacy 32 bit equivalent
PM addresses.  Add a acpi_force_32bit_fadt_addr to set the ACPICA
acpi_gbl_use32_bit_fadt_addresses to TRUE to force this override.

Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 Documentation/kernel-parameters.txt |  6 ++++++
 drivers/acpi/tables.c               | 10 ++++++++++
 2 files changed, 16 insertions(+)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 3ea869d..3782024 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -193,6 +193,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			(e.g. thinkpad_acpi, sony_acpi, etc.) instead
 			of the ACPI video.ko driver.
 
+	acpi_force_32bit_fadt_addr
+			force FADT to use 32 bit addresses rather than the
+			64 bit X_* addresses. Some firmware have broken 64
+			bit addresses for force ACPI ignore these and use
+			the older legacy 32 bit addresses.
+
 	acpica_no_return_repair [HW, ACPI]
 			Disable AML predefined validation mechanism
 			This mechanism can repair the evaluation result to make
diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
index 6c0f079..ebdf564 100644
--- a/drivers/acpi/tables.c
+++ b/drivers/acpi/tables.c
@@ -484,3 +484,13 @@ static int __init acpi_force_table_verification_setup(char *s)
 }
 
 early_param("acpi_force_table_verification", acpi_force_table_verification_setup);
+
+static int __init acpi_force_32bit_fadt_addr(char *s)
+{
+	pr_info("Forcing 32 Bit FADT addresses\n");
+	acpi_gbl_use32_bit_fadt_addresses = TRUE;
+
+	return 0;
+}
+
+early_param("acpi_force_32bit_fadt_addr", acpi_force_32bit_fadt_addr);
-- 
1.9.1