[PATCH v4 3/3] x86/acpi: take rsdp address for boot params if available

Juergen Gross
2018-10-09T10:54:45Z

In case the rsdp address in struct boot_params is specified don't try
to find the table by searching, but take the address directly as set
by the boot loader.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
V3: use a generic retrieval function with a __weak annotated default
function (Ingo Molnar)

V4: check boot params version before using acpi_rsdp_addr
use x86_init structure instead of __weak
---
arch/x86/include/asm/acpi.h | 2 ++
arch/x86/kernel/acpi/boot.c | 6 ++++++
arch/x86/kernel/x86_init.c | 3 +--
3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/acpi.h b/arch/x86/include/asm/acpi.h
index a303d7b7d763..e9057ebff76c 100644
--- a/arch/x86/include/asm/acpi.h
+++ b/arch/x86/include/asm/acpi.h
@@ -142,6 +142,8 @@ static inline u64 acpi_arch_get_root_pointer(void)

void acpi_generic_reduced_hw_init(void);

+u64 x86_default_get_root_pointer(void);
+
#else /* !CONFIG_ACPI */

#define acpi_lapic 0
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 3b20607d581b..e8fea7ffa306 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -48,6 +48,7 @@
#include <asm/mpspec.h>
#include <asm/smp.h>
#include <asm/i8259.h>
+#include <asm/setup.h>

#include "sleep.h" /* To include x86_acpi_suspend_lowlevel */
static int __initdata acpi_force = 0;
@@ -1771,3 +1772,8 @@ void __init arch_reserve_mem_area(acpi_physical_address addr, size_t size)
e820__range_add(addr, size, E820_TYPE_ACPI);
e820__update_table_print();
}
+
+u64 x86_default_get_root_pointer(void)
+{
+ return boot_params.hdr.acpi_rsdp_addr;
+}
diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
index 2792b5573818..50a2b492fdd6 100644
--- a/arch/x86/kernel/x86_init.c
+++ b/arch/x86/kernel/x86_init.c
@@ -31,7 +31,6 @@ static int __init iommu_init_noop(void) { return 0; }
static void iommu_shutdown_noop(void) { }
static bool __init bool_x86_init_noop(void) { return false; }
static void x86_op_int_noop(int cpu) { }
-static u64 u64_x86_init_noop(void) { return 0; }

/*
* The platform setup functions are preset with the default functions
@@ -96,7 +95,7 @@ struct x86_init_ops x86_init __initdata = {
},

.acpi = {
- .get_root_pointer = u64_x86_init_noop,
+ .get_root_pointer = x86_default_get_root_pointer,
.reduced_hw_early_init = acpi_generic_reduced_hw_init,
},
};
--
2.16.4