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authorLinus Torvalds <torvalds@linux-foundation.org>2012-12-14 10:08:40 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-12-14 10:08:40 -0800
commitd42b3a2906a10b732ea7d7f849d49be79d242ef0 (patch)
tree1f4f2387bf53f8015aa87eb9c05ba8316cb5ed50 /Documentation
parent18dd0bf22b6f0c1bd5e4e813a42245ed86ec57b6 (diff)
parente83af1f18c78c7b6aa720beecc927ecc8afd3647 (diff)
Merge branch 'core-efi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 EFI update from Peter Anvin: "EFI tree, from Matt Fleming. Most of the patches are the new efivarfs filesystem by Matt Garrett & co. The balance are support for EFI wallclock in the absence of a hardware-specific driver, and various fixes and cleanups." * 'core-efi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits) efivarfs: Make efivarfs_fill_super() static x86, efi: Check table header length in efi_bgrt_init() efivarfs: Use query_variable_info() to limit kmalloc() efivarfs: Fix return value of efivarfs_file_write() efivarfs: Return a consistent error when efivarfs_get_inode() fails efivarfs: Make 'datasize' unsigned long efivarfs: Add unique magic number efivarfs: Replace magic number with sizeof(attributes) efivarfs: Return an error if we fail to read a variable efi: Clarify GUID length calculations efivarfs: Implement exclusive access for {get,set}_variable efivarfs: efivarfs_fill_super() ensure we clean up correctly on error efivarfs: efivarfs_fill_super() ensure we free our temporary name efivarfs: efivarfs_fill_super() fix inode reference counts efivarfs: efivarfs_create() ensure we drop our reference on inode on error efivarfs: efivarfs_file_read ensure we free data in error paths x86-64/efi: Use EFI to deal with platform wall clock (again) x86/kernel: remove tboot 1:1 page table creation code x86, efi: 1:1 pagetable mapping for virtual EFI calls x86, mm: Include the entire kernel memory map in trampoline_pgd ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/filesystems/00-INDEX2
-rw-r--r--Documentation/filesystems/efivarfs.txt16
2 files changed, 18 insertions, 0 deletions
diff --git a/Documentation/filesystems/00-INDEX b/Documentation/filesystems/00-INDEX
index 8c624a18f67d..7b52ba7bf32a 100644
--- a/Documentation/filesystems/00-INDEX
+++ b/Documentation/filesystems/00-INDEX
@@ -38,6 +38,8 @@ dnotify_test.c
- example program for dnotify
ecryptfs.txt
- docs on eCryptfs: stacked cryptographic filesystem for Linux.
+efivarfs.txt
+ - info for the efivarfs filesystem.
exofs.txt
- info, usage, mount options, design about EXOFS.
ext2.txt
diff --git a/Documentation/filesystems/efivarfs.txt b/Documentation/filesystems/efivarfs.txt
new file mode 100644
index 000000000000..c477af086e65
--- /dev/null
+++ b/Documentation/filesystems/efivarfs.txt
@@ -0,0 +1,16 @@
+
+efivarfs - a (U)EFI variable filesystem
+
+The efivarfs filesystem was created to address the shortcomings of
+using entries in sysfs to maintain EFI variables. The old sysfs EFI
+variables code only supported variables of up to 1024 bytes. This
+limitation existed in version 0.99 of the EFI specification, but was
+removed before any full releases. Since variables can now be larger
+than a single page, sysfs isn't the best interface for this.
+
+Variables can be created, deleted and modified with the efivarfs
+filesystem.
+
+efivarfs is typically mounted like this,
+
+ mount -t efivarfs none /sys/firmware/efi/efivars