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.

[ Impact: new feature to support more bootloaders ]

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

4 files changed, 16 insertions, 4 deletions

diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index a0b426978d55..68c3bfbaff24 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 433adaebf9b6..1724e8de317c 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 fcf4d92e7e04..6384d25121ca 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 b4158439bf63..2b093451aec9 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;