diff --git a/Documentation/x86/boot.txt b/Documentation/x86/boot.txt
index 5e9b826b5f62fd1cf8dfcae07fc5bde66594428b..7727db8f94bce6af42b5cc1920bf2a46798ad0b4 100644
--- a/Documentation/x86/boot.txt
+++ b/Documentation/x86/boot.txt
@@ -61,6 +61,18 @@ Protocol 2.12: (Kernel 3.8) Added the xloadflags field and extension fields
to struct boot_params for loading bzImage and ramdisk
above 4G in 64bit.
+Protocol 2.13: (Kernel 3.14) Support 32- and 64-bit flags being set in
+ xloadflags to support booting a 64-bit kernel from 32-bit
+ EFI
+
+Protocol 2.14: (Kernel 4.20) Added acpi_rsdp_addr holding the physical
+ address of the ACPI RSDP table.
+ The bootloader updates version with:
+ 0x8000 | min(kernel-version, bootloader-version)
+ kernel-version being the protocol version supported by
+ the kernel and bootloader-version the protocol version
+ supported by the bootloader.
+
**** MEMORY LAYOUT
The traditional memory map for the kernel loader, used for Image or
@@ -197,6 +209,7 @@ Offset Proto Name Meaning
0258/8 2.10+ pref_address Preferred loading address
0260/4 2.10+ init_size Linear memory required during initialization
0264/4 2.11+ handover_offset Offset of handover entry point
+0268/8 2.14+ acpi_rsdp_addr Physical address of RSDP table
(1) For backwards compatibility, if the setup_sects field contains 0, the
real value is 4.
@@ -309,7 +322,7 @@ Protocol: 2.00+
Contains the magic number "HdrS" (0x53726448).
Field name: version
-Type: read
+Type: modify
Offset/size: 0x206/2
Protocol: 2.00+
@@ -317,6 +330,12 @@ Protocol: 2.00+
e.g. 0x0204 for version 2.04, and 0x0a11 for a hypothetical version
10.17.
+ Up to protocol version 2.13 this information is only read by the
+ bootloader. From protocol version 2.14 onwards the bootloader will
+ write the used protocol version or-ed with 0x8000 to the field. The
+ used protocol version will be the minimum of the supported protocol
+ versions of the bootloader and the kernel.
+
Field name: realmode_swtch
Type: modify (optional)
Offset/size: 0x208/4
@@ -744,6 +763,17 @@ Offset/size: 0x264/4
See EFI HANDOVER PROTOCOL below for more details.
+Field name: acpi_rsdp_addr
+Type: write
+Offset/size: 0x268/8
+Protocol: 2.14+
+
+ This field can be set by the boot loader to tell the kernel the
+ physical address of the ACPI RSDP table.
+
+ A value of 0 indicates the kernel should fall back to the standard
+ methods to locate the RSDP.
+
**** THE IMAGE CHECKSUM
diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 850b8762e889656c43da518520c5bae60e945e3d..4c881c850125c674145e4627078c91ce4a453f0e 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -300,7 +300,7 @@ _start:
# Part 2 of the header, from the old setup.S
.ascii "HdrS" # header signature
- .word 0x020d # header version number (>= 0x0105)
+ .word 0x020e # header version number (>= 0x0105)
# or else old loadlin-1.5 will fail)
.globl realmode_swtch
realmode_swtch: .word 0, 0 # default_switch, SETUPSEG
@@ -558,6 +558,10 @@ pref_address: .quad LOAD_PHYSICAL_ADDR # preferred load addr
init_size: .long INIT_SIZE # kernel initialization size
handover_offset: .long 0 # Filled in by build.c
+acpi_rsdp_addr: .quad 0 # 64-bit physical pointer to the
+ # ACPI RSDP table, added with
+ # version 2.14
+
# End of setup header #####################################################
.section ".entrytext", "ax"
diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
index b85a7c54c6a13b51f27b26f13a2dd52f148547a7..0f842104862c3b063cf806566736274d9df3faea 100644
--- a/arch/x86/include/asm/x86_init.h
+++ b/arch/x86/include/asm/x86_init.h
@@ -303,4 +303,6 @@ extern void x86_init_noop(void);
extern void x86_init_uint_noop(unsigned int unused);
extern bool x86_pnpbios_disabled(void);
+void x86_verify_bootdata_version(void);
+
#endif
diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h
index a06cbf01974462de6cf163fb87008453fd6c019c..22f89d040dddce756a53fc94c2bb1fbcf3abcb4b 100644
--- a/arch/x86/include/uapi/asm/bootparam.h
+++ b/arch/x86/include/uapi/asm/bootparam.h
@@ -16,6 +16,9 @@
#define RAMDISK_PROMPT_FLAG 0x8000
#define RAMDISK_LOAD_FLAG 0x4000
+/* version flags */
+#define VERSION_WRITTEN 0x8000
+
/* loadflags */
#define LOADED_HIGH (1<<0)
#define KASLR_FLAG (1<<1)
@@ -86,6 +89,7 @@ struct setup_header {
__u64 pref_address;
__u32 init_size;
__u32 handover_offset;
+ __u64 acpi_rsdp_addr;
} __attribute__((packed));
struct sys_desc_table {
diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c
index ec6fefbfd3c0454b009a2a7a04a76edc44b8c5e8..76fa3b8365985783332b99186b10cdc9a15dd169 100644
--- a/arch/x86/kernel/head32.c
+++ b/arch/x86/kernel/head32.c
@@ -37,6 +37,7 @@ asmlinkage __visible void __init i386_start_kernel(void)
cr4_init_shadow();
sanitize_boot_params(&boot_params);
+ x86_verify_bootdata_version();
x86_early_init_platform_quirks();
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index ddee1f0870c4b091cae110f35d92a2d87a05d8b6..5dc377dc9d7b5a25027e2d6358696bff2f56d635 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -457,6 +457,8 @@ void __init x86_64_start_reservations(char *real_mode_data)
if (!boot_params.hdr.version)
copy_bootdata(__va(real_mode_data));
+ x86_verify_bootdata_version();
+
x86_early_init_platform_quirks();
switch (boot_params.hdr.hardware_subarch) {
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index b4866badb235a64be119989e642764d0becac65f..8e226b7a175341afc3cd4028387e45139299919f 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1281,6 +1281,23 @@ void __init setup_arch(char **cmdline_p)
unwind_init();
}
+/*
+ * From boot protocol 2.14 onwards we expect the bootloader to set the
+ * version to "0x8000 | <used version>". In case we find a version >= 2.14
+ * without the 0x8000 we assume the boot loader supports 2.13 only and
+ * reset the version accordingly. The 0x8000 flag is removed in any case.
+ */
+void __init x86_verify_bootdata_version(void)
+{
+ if (boot_params.hdr.version & VERSION_WRITTEN)
+ boot_params.hdr.version &= ~VERSION_WRITTEN;
+ else if (boot_params.hdr.version >= 0x020e)
+ boot_params.hdr.version = 0x020d;
+
+ if (boot_params.hdr.version < 0x020e)
+ boot_params.hdr.acpi_rsdp_addr = 0;
+}
+
#ifdef CONFIG_X86_32
static struct resource video_ram_resource = {