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>

1 files changed, 8 insertions, 2 deletions

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;