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authorDave Young <dyoung@redhat.com>2013-12-20 18:02:21 +0800
committerMatt Fleming <matt.fleming@intel.com>2013-12-29 13:09:07 +0000
commit5039e316dde3fb71c79e95e97c5bca8e4724d8f2 (patch)
tree9446e8ce0df0d9849bfec4fab93bd30f59d7c919 /Documentation
parent456a29ddada79198c5965300e04103c40c481f62 (diff)
x86: Export x86 boot_params to sysfs
kexec-tools use boot_params for getting the 1st kernel hardware_subarch, the kexec kernel EFI runtime support also needs to read the old efi_info from boot_params. Currently it exists in debugfs which is not a good place for such infomation. Per HPA, we should avoid "sploit debugfs". In this patch /sys/kernel/boot_params are exported, also the setup_data is exported as a subdirectory. kexec-tools is using debugfs for hardware_subarch for a long time now so we're not removing it yet. Structure is like below: /sys/kernel/boot_params |__ data /* boot_params in binary*/ |__ setup_data | |__ 0 /* the first setup_data node */ | | |__ data /* setup_data node 0 in binary*/ | | |__ type /* setup_data type of setup_data node 0, hex string */ [snip] |__ version /* boot protocal version (in hex, "0x" prefixed)*/ Signed-off-by: Dave Young <dyoung@redhat.com> Acked-by: Borislav Petkov <bp@suse.de> Tested-by: Toshi Kani <toshi.kani@hp.com> Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/ABI/testing/sysfs-kernel-boot_params38
1 files changed, 38 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-kernel-boot_params b/Documentation/ABI/testing/sysfs-kernel-boot_params
new file mode 100644
index 000000000000..eca38ce2852d
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-kernel-boot_params
@@ -0,0 +1,38 @@
+What: /sys/kernel/boot_params
+Date: December 2013
+Contact: Dave Young <dyoung@redhat.com>
+Description: The /sys/kernel/boot_params directory contains two
+ files: "data" and "version" and one subdirectory "setup_data".
+ It is used to export the kernel boot parameters of an x86
+ platform to userspace for kexec and debugging purpose.
+
+ If there's no setup_data in boot_params the subdirectory will
+ not be created.
+
+ "data" file is the binary representation of struct boot_params.
+
+ "version" file is the string representation of boot
+ protocol version.
+
+ "setup_data" subdirectory contains the setup_data data
+ structure in boot_params. setup_data is maintained in kernel
+ as a link list. In "setup_data" subdirectory there's one
+ subdirectory for each link list node named with the number
+ of the list nodes. The list node subdirectory contains two
+ files "type" and "data". "type" file is the string
+ representation of setup_data type. "data" file is the binary
+ representation of setup_data payload.
+
+ The whole boot_params directory structure is like below:
+ /sys/kernel/boot_params
+ |__ data
+ |__ setup_data
+ | |__ 0
+ | | |__ data
+ | | |__ type
+ | |__ 1
+ | |__ data
+ | |__ type
+ |__ version
+
+Users: Kexec