doc: Add documentation for bootloader_{type,version}
Add documentation for kernel/bootloader_type and
kernel/bootloader_version to sysctl/kernel.txt. This should really
have been done a long time ago.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Shen Feng <shen@cn.fujitsu.com>
diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index 8f7a0e7..3894eaa 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -19,6 +19,8 @@
show up in /proc/sys/kernel:
- acpi_video_flags
- acct
+- bootloader_type [ X86 only ]
+- bootloader_version [ X86 only ]
- callhome [ S390 only ]
- auto_msgmni
- core_pattern
@@ -93,6 +95,35 @@
==============================================================
+bootloader_type:
+
+x86 bootloader identification
+
+This gives the bootloader type number as indicated by the bootloader,
+shifted left by 4, and OR'd with the low four bits of the bootloader
+version. The reason for this encoding is that this used to match the
+type_of_loader field in the kernel header; the encoding is kept for
+backwards compatibility. That is, if the full bootloader type number
+is 0x15 and the full version number is 0x234, this file will contain
+the value 340 = 0x154.
+
+See the type_of_loader and ext_loader_type fields in
+Documentation/x86/boot.txt for additional information.
+
+==============================================================
+
+bootloader_version:
+
+x86 bootloader version
+
+The complete bootloader version number. In the example above, this
+file will contain the value 564 = 0x234.
+
+See the type_of_loader and ext_loader_ver fields in
+Documentation/x86/boot.txt for additional information.
+
+==============================================================
+
callhome:
Controls the kernel's callhome behavior in case of a kernel panic.
