[tip:x86/kbuild-phys] x86: add extension fields for bootloader type and version
From: tip-bot for H. Peter Anvin
Date: Thu May 07 2009 - 20:42:02 EST
Commit-ID: 3d280bb6fc862ea3a376841a529dfc683715ca05
Gitweb: http://git.kernel.org/tip/3d280bb6fc862ea3a376841a529dfc683715ca05
Author: H. Peter Anvin <hpa@xxxxxxxxx>
AuthorDate: Thu, 7 May 2009 16:54:11 -0700
Committer: H. Peter Anvin <hpa@xxxxxxxxx>
CommitDate: Thu, 7 May 2009 16:54:11 -0700
x86: add extension fields for bootloader type and version
A long ago, in days of yore, it all began with a god named Thor.
There were vikings and boats and some plans for a Linux kernel
header. Unfortunately, a single 8-bit field was used for bootloader
type and version. This has generally worked without *too* much pain,
but we're getting close to flat running out of ID fields.
Add extension fields for both type and version. The type will be
extended if it the old field is 0xE; the version is a simple MSB
extension.
Keep /proc/sys/kernel/bootloader_type containing
(type << 4) + (ver & 0xf) for backwards compatiblity, but also add
/proc/sys/kernel/bootloader_version which contains the full version
number.
Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxx>
LKML-Reference: <49823683.6060201@xxxxxxxxx>
---
Documentation/x86/boot.txt | 57 ++++++++++++++++++++++++++++++++++---
arch/x86/boot/header.S | 6 +++-
arch/x86/include/asm/bootparam.h | 3 +-
arch/x86/include/asm/processor.h | 1 +
arch/x86/kernel/setup.c | 10 +++++-
kernel/sysctl.c | 8 +++++
6 files changed, 76 insertions(+), 9 deletions(-)
diff --git a/Documentation/x86/boot.txt b/Documentation/x86/boot.txt
index 093f838..01b5542 100644
--- a/Documentation/x86/boot.txt
+++ b/Documentation/x86/boot.txt
@@ -52,7 +52,8 @@ Protocol 2.09: (Kernel 2.6.26) Added a field of 64-bit physical
Protocol 2.10: (Kernel 2.6.31) Added the runtime_start and
runtime_size fields for the post-decompression address
- and memory requirements of the kernel.
+ and memory requirements of the kernel. The previous "pad1"
+ field reclaimed as extended boot loader ID.
**** MEMORY LAYOUT
@@ -172,7 +173,8 @@ Offset Proto Name Meaning
021C/4 2.00+ ramdisk_size initrd size (set by boot loader)
0220/4 2.00+ bootsect_kludge DO NOT USE - for bootsect.S use only
0224/2 2.01+ heap_end_ptr Free memory after setup end
-0226/2 N/A pad1 Unused
+0226/1 2.02+(3 ext_loader_ver Extended boot loader version
+0227/1 2.02+(3 ext_loader_type Extended boot loader ID
0228/4 2.02+ cmd_line_ptr 32-bit pointer to the kernel command line
022C/4 2.03+ ramdisk_max Highest legal initrd address
0230/4 2.05+ kernel_alignment Physical addr alignment required for kernel
@@ -196,6 +198,8 @@ Offset Proto Name Meaning
field are unusable, which means the size of a bzImage kernel
cannot be determined.
+(3) Ignored, but safe to set, for boot protocols 2.02-2.09.
+
If the "HdrS" (0x53726448) magic number is not found at offset 0x202,
the boot protocol version is "old". Loading an old kernel, the
following parameters should be assumed:
@@ -349,18 +353,32 @@ Protocol: 2.00+
0xTV here, where T is an identifier for the boot loader and V is
a version number. Otherwise, enter 0xFF here.
+ For boot loader IDs above T = 0xD, write T = 0xE to this field and
+ write the extended ID minus 0x10 to the ext_loader_type field.
+ Similarly, the ext_loader_ver field can be used to provide more than
+ four bits for the bootloader version.
+
+ For example, for T = 0x15, V = 0x234, write:
+
+ type_of_loader <- 0xE4
+ ext_loader_type <- 0x05
+ ext_loader_ver <- 0x23
+
Assigned boot loader ids:
0 LILO (0x00 reserved for pre-2.00 bootloader)
1 Loadlin
2 bootsect-loader (0x20, all other values reserved)
- 3 SYSLINUX
- 4 EtherBoot
+ 3 Syslinux
+ 4 Etherboot/gPXE
5 ELILO
7 GRUB
- 8 U-BOOT
+ 8 U-Boot
9 Xen
A Gujin
B Qemu
+ C Arcturus Networks uCbootloader
+ E Extended (see ext_loader_type)
+ F Special (0xFF = undefined)
Please contact <hpa@xxxxxxxxx> if you need a bootloader ID
value assigned.
@@ -459,6 +477,35 @@ Protocol: 2.01+
Set this field to the offset (from the beginning of the real-mode
code) of the end of the setup stack/heap, minus 0x0200.
+Field name: ext_loader_ver
+Type: write (optional)
+Offset/size: 0x226/1
+Protocol: 2.02+
+
+ This field is used as an extension of the version number in the
+ type_of_loader field. The total version number is considered to be
+ (type_of_loader & 0x0f) + (ext_loader_ver << 4).
+
+ The use of this field is boot loader specific. If not written, it
+ is zero.
+
+ Kernels prior to 2.6.31 did not recognize this field, but it is safe
+ to write for protocol version 2.02 or higher.
+
+Field name: ext_loader_type
+Type: write (obligatory if (type_of_loader & 0xf0) == 0xe0)
+Offset/size: 0x227/1
+Protocol: 2.02+
+
+ This field is used as an extension of the type number in
+ type_of_loader field. If the type in type_of_loader is 0xE, then
+ the actual type is (ext_loader_type + 0x10).
+
+ This field is ignored if the type in type_of_loader is not 0xE.
+
+ Kernels prior to 2.6.31 did not recognize this field, but it is safe
+ to write for protocol version 2.02 or higher.
+
Field name: cmd_line_ptr
Type: write (obligatory)
Offset/size: 0x228/4
diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 0491fc4..5e96bb2 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -169,7 +169,11 @@ heap_end_ptr: .word _end+STACK_SIZE-512
# end of setup code can be used by setup
# for local heap purposes.
-pad1: .word 0
+ext_loader_ver:
+ .byte 0 # Extended boot loader version
+ext_loader_type:
+ .byte 0 # Extended boot loader type
+
cmd_line_ptr: .long 0 # (Header version 0x0202 or later)
# If nonzero, a 32-bit pointer
# to the kernel command line.
diff --git a/arch/x86/include/asm/bootparam.h b/arch/x86/include/asm/bootparam.h
index dd924b5..5b02f05 100644
--- a/arch/x86/include/asm/bootparam.h
+++ b/arch/x86/include/asm/bootparam.h
@@ -50,7 +50,8 @@ struct setup_header {
__u32 ramdisk_size;
__u32 bootsect_kludge;
__u16 heap_end_ptr;
- __u16 _pad1;
+ __u8 ext_loader_ver;
+ __u8 ext_loader_type;
__u32 cmd_line_ptr;
__u32 initrd_addr_max;
__u32 kernel_alignment;
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index fcf4d92..6384d25 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -814,6 +814,7 @@ extern unsigned int BIOS_revision;
/* Boot loader type from the setup header: */
extern int bootloader_type;
+extern int bootloader_version;
extern char ignore_fpu_irq;
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index b415843..2b09345 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -214,8 +214,8 @@ unsigned long mmu_cr4_features;
unsigned long mmu_cr4_features = X86_CR4_PAE;
#endif
-/* Boot loader ID as an integer, for the benefit of proc_dointvec */
-int bootloader_type;
+/* Boot loader ID and version as integers, for the benefit of proc_dointvec */
+int bootloader_type, bootloader_version;
/*
* Setup options
@@ -706,6 +706,12 @@ void __init setup_arch(char **cmdline_p)
#endif
saved_video_mode = boot_params.hdr.vid_mode;
bootloader_type = boot_params.hdr.type_of_loader;
+ if ((bootloader_type >> 4) == 0xe) {
+ bootloader_type &= 0xf;
+ bootloader_type |= (boot_params.hdr.ext_loader_type+0x10) << 4;
+ }
+ bootloader_version = bootloader_type & 0xf;
+ bootloader_version |= boot_params.hdr.ext_loader_ver << 4;
#ifdef CONFIG_BLK_DEV_RAM
rd_image_start = boot_params.hdr.ram_size & RAMDISK_IMAGE_START_MASK;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index e3d2c7d..cf91c93 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -729,6 +729,14 @@ static struct ctl_table kern_table[] = {
},
{
.ctl_name = CTL_UNNUMBERED,
+ .procname = "bootloader_version",
+ .data = &bootloader_version,
+ .maxlen = sizeof (int),
+ .mode = 0444,
+ .proc_handler = &proc_dointvec,
+ },
+ {
+ .ctl_name = CTL_UNNUMBERED,
.procname = "kstack_depth_to_print",
.data = &kstack_depth_to_print,
.maxlen = sizeof(int),
--
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