x86/acpi, x86/boot: Take RSDP address from boot params if available

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. Suggested-by: "H. Peter Anvin" <[email protected]> Signed-off-by: Juergen Gross <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
btm · Nov 20, 2018 · e6e094e · e6e094e
1 parent 3841840
commit e6e094e
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diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h
@@ -155,7 +155,8 @@ struct boot_params {
 	__u8  _pad2[4];					/* 0x054 */
 	__u64  tboot_addr;				/* 0x058 */
 	struct ist_info ist_info;			/* 0x060 */
-	__u8  _pad3[16];				/* 0x070 */
+	__u64 acpi_rsdp_addr;				/* 0x070 */
+	__u8  _pad3[8];					/* 0x078 */
 	__u8  hd0_info[16];	/* obsolete! */		/* 0x080 */
 	__u8  hd1_info[16];	/* obsolete! */		/* 0x090 */
 	struct sys_desc_table sys_desc_table; /* obsolete! */	/* 0x0a0 */

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
@@ -1776,5 +1776,5 @@ void __init arch_reserve_mem_area(acpi_physical_address addr, size_t size)
 
 u64 x86_default_get_root_pointer(void)
 {
-	return 0;
+	return boot_params.acpi_rsdp_addr;
 }