On Wed, 27 Nov 2013 15:31:50 -0800, Roy Franz <roy.franz@xxxxxxxxxx> wrote: > Update efi-stub.txt documentation to be more general > and not x86 specific. Add ARM only "dtb=" command > line option description. > > Signed-off-by: Roy Franz <roy.franz@xxxxxxxxxx> Acked-by: Grant Likely <grant.likely@xxxxxxxxxx> > --- > Documentation/efi-stub.txt | 27 ++++++++++++++++++++------- > 1 file changed, 20 insertions(+), 7 deletions(-) > > diff --git a/Documentation/efi-stub.txt b/Documentation/efi-stub.txt > index 44e6bb6..19e897c 100644 > --- a/Documentation/efi-stub.txt > +++ b/Documentation/efi-stub.txt > @@ -1,13 +1,16 @@ > The EFI Boot Stub > --------------------------- > > -On the x86 platform, a bzImage can masquerade as a PE/COFF image, > -thereby convincing EFI firmware loaders to load it as an EFI > -executable. The code that modifies the bzImage header, along with the > -EFI-specific entry point that the firmware loader jumps to are > -collectively known as the "EFI boot stub", and live in > +On the x86 and ARM platforms, a kernel zImage/bzImage can masquerade > +as a PE/COFF image, thereby convincing EFI firmware loaders to load > +it as an EFI executable. The code that modifies the bzImage header, > +along with the EFI-specific entry point that the firmware loader > +jumps to are collectively known as the "EFI boot stub", and live in > arch/x86/boot/header.S and arch/x86/boot/compressed/eboot.c, > -respectively. > +respectively. For ARM the EFI stub is implemented in > +arch/arm/boot/compressed/efi-header.S and > +arch/arm/boot/compressed/efi-stub.c. EFI stub code that is shared > +between architectures is in drivers/firmware/efi/efi-stub-helper.c. > > By using the EFI boot stub it's possible to boot a Linux kernel > without the use of a conventional EFI boot loader, such as grub or > @@ -23,7 +26,9 @@ The bzImage located in arch/x86/boot/bzImage must be copied to the EFI > System Partiion (ESP) and renamed with the extension ".efi". Without > the extension the EFI firmware loader will refuse to execute it. It's > not possible to execute bzImage.efi from the usual Linux file systems > -because EFI firmware doesn't have support for them. > +because EFI firmware doesn't have support for them. For ARM the > +arch/arm/boot/zImage should be copied to the system partition, and it > +may not need to be renamed. > > > **** Passing kernel parameters from the EFI shell > @@ -63,3 +68,11 @@ Notice how bzImage.efi can be specified with a relative path. That's > because the image we're executing is interpreted by the EFI shell, > which understands relative paths, whereas the rest of the command line > is passed to bzImage.efi. > + > + > +**** The "dtb=" option > + > +For the ARM architecture, we also need to be able to provide a device > +tree to the kernel. This is done with the "dtb=" command line option, > +and is process in the same manner as the "initrd=" option that is described > +above. > -- > 1.7.10.4 > -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
