On 06/25/2013 02:11 PM, Leif Lindholm wrote: > This patch provides documentation of the [U]EFI runtime services and > configuration features. > > Signed-off-by: Leif Lindholm <leif.lindholm@xxxxxxxxxx> > --- > Documentation/arm/00-INDEX | 3 +++ > Documentation/arm/uefi.txt | 39 +++++++++++++++++++++++++++++++++++++++ > 2 files changed, 42 insertions(+) > create mode 100644 Documentation/arm/uefi.txt > > diff --git a/Documentation/arm/00-INDEX b/Documentation/arm/00-INDEX > index 4978456..87e01d1 100644 > --- a/Documentation/arm/00-INDEX > +++ b/Documentation/arm/00-INDEX > @@ -36,3 +36,6 @@ nwfpe/ > - NWFPE floating point emulator documentation > swp_emulation > - SWP/SWPB emulation handler/logging description > + > +uefi.txt > + - [U]EFI configuration and runtime services documentation > diff --git a/Documentation/arm/uefi.txt b/Documentation/arm/uefi.txt > new file mode 100644 > index 0000000..5c48271 > --- /dev/null > +++ b/Documentation/arm/uefi.txt > @@ -0,0 +1,39 @@ > +The nomenclature EFI and UEFI are used interchangeably in this document. > + > +The implementation depends on receiving pointers to the UEFI memory map > +and System Table in a Flattened Device Tree - so is only available with > +CONFIG_OF. > + > +It (early) parses the FDT for the following parameters: > +- 'efi-system-table': > + Physical address of the system table. (required) > +- 'efi-runtime-mmap': > + Physical address of an EFI memory map, containing at least > + the regions to be preserved. (required) > +- 'efi-runtime-mmap-size': > + Size in bytes of the provided memory map. (required) > +- 'efi-mmap-desc-size': > + Size of each descriptor in the memory map. (override default) > +- 'efi-mmap-desc-ver': > + Memory descriptor format version. (override default) > + > +Since UEFI firmware on ARM systems are required to use a 1:1 memory map > +even on LPAE-capable systems, the above fields are 32-bit regardless. > + > +It also depends on early_ioremap to parse the memory map and preserve > +the regions required for runtime services. > + > +For actually enabling [U]EFI support, enable: > +- CONFIG_EFI=y > +- CONFIG_EFI_VARS=y or m > + > +After the kernel has mapped the required regions into its address space, > +a SetVirtualAddressMap() call is made into UEFI in order to update > +relocations. This call must be performed with all the code in a 1:1 > +mapping. This implementation achieves this by temporarily disabling the > +MMU for the duration of this call. This can only be done safely: > +- before secondary CPUs are brought online. > +- after early_initcalls have completed, sinze it uses setup_mm_for_reboot(). since > + > +For verbose debug messages, specify 'uefi_debug' on the kernel command > +line. > Christopher -- Employee of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by the Linux Foundation. -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
