diff options
| author | Borislav Petkov <bp@suse.de> | 2013-10-31 17:25:08 +0100 |
|---|---|---|
| committer | Matt Fleming <matt.fleming@intel.com> | 2013-11-02 11:09:36 +0000 |
| commit | d2f7cbe7b26a74dbbbf8f325b2a6fd01bc34032c (patch) | |
| tree | 69d2c1f92120fa532c77cf8634418b7622d55692 /Documentation | |
| parent | 82f0712ca0f947170e785300b5c39d9c25e2f6ff (diff) | |
x86/efi: Runtime services virtual mapping
We map the EFI regions needed for runtime services non-contiguously,
with preserved alignment on virtual addresses starting from -4G down
for a total max space of 64G. This way, we provide for stable runtime
services addresses across kernels so that a kexec'd kernel can still use
them.
Thus, they're mapped in a separate pagetable so that we don't pollute
the kernel namespace.
Add an efi= kernel command line parameter for passing miscellaneous
options and chicken bits from the command line.
While at it, add a chicken bit called "efi=old_map" which can be used as
a fallback to the old runtime services mapping method in case there's
some b0rkage with a particular EFI implementation (haha, it is hard to
hold up the sarcasm here...).
Also, add the UEFI RT VA space to Documentation/x86/x86_64/mm.txt.
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/kernel-parameters.txt | 6 | ||||
| -rw-r--r-- | Documentation/x86/x86_64/mm.txt | 7 |
2 files changed, 13 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 7a0f202d482e..ed43e92b0e7e 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -835,6 +835,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted. edd= [EDD] Format: {"off" | "on" | "skip[mbr]"} + efi= [EFI] + Format: { "old_map" } + old_map [X86-64]: switch to the old ioremap-based EFI + runtime services mapping. 32-bit still uses this one by + default. + efi_no_storage_paranoia [EFI; X86] Using this parameter you can use more than 50% of your efi variable storage. Use this parameter only if diff --git a/Documentation/x86/x86_64/mm.txt b/Documentation/x86/x86_64/mm.txt index 881582f75c9c..c584a51add15 100644 --- a/Documentation/x86/x86_64/mm.txt +++ b/Documentation/x86/x86_64/mm.txt @@ -28,4 +28,11 @@ reference. Current X86-64 implementations only support 40 bits of address space, but we support up to 46 bits. This expands into MBZ space in the page tables. +->trampoline_pgd: + +We map EFI runtime services in the aforementioned PGD in the virtual +range of 64Gb (arbitrarily set, can be raised if needed) + +0xffffffef00000000 - 0xffffffff00000000 + -Andi Kleen, Jul 2004 |