Messages in this thread | | | Date | Tue, 13 Sep 2011 16:33:05 +0200 | From | Maarten Lankhorst <> | Subject | Re: [PATCH v2 10/10] x86, efi: EFI boot stub support |
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Hey Matt,
On 09/12/2011 04:34 PM, Matt Fleming wrote: > From: Matt Fleming <matt.fleming@intel.com> > > There is currently a large divide between kernel development and the > development of EFI boot loaders. The idea behind this patch is to give > the kernel developers full control over the EFI boot process. As > H. Peter Anvin put it, > > "The 'kernel carries its own stub' approach been very successful in > dealing with BIOS, and would make a lot of sense to me for EFI as > well." > > This patch introduces an EFI boot stub that allows an x86 bzImage to > be loaded and executed by EFI firmware. The bzImage appears to the > firmware as an EFI application. Luckily there are enough free bits > within the bzImage header so that it can masquerade as an EFI > application, thereby coercing the EFI firmware into loading it and > jumping to its entry point. The beauty of this masquerading approach > is that both BIOS and EFI boot loaders can still load and run the same > bzImage, thereby allowing a single kernel image to work in any boot > environment. > > The EFI boot stub supports multiple initrds, but they must exist on > the same partition as the bzImage. Command-line arguments for the > kernel can be appended after the bzImage name when run from the EFI > shell, e.g. > > Shell> bzImage console=ttyS0 root=/dev/sdb initrd=initrd.img > > Cc: H. Peter Anvin <hpa@linux.intel.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Ingo Molnar <mingo@elte.hu> > Cc: Mike Waychison <mikew@google.com> > Cc: Matthew Garrett <mjg@redhat.com> > Cc: Andi Kleen <andi@firstfloor.org> > Cc: Maarten Lankhorst <m.b.lankhorst@gmail.com> > Signed-off-by: Matt Fleming <matt.fleming@intel.com> > --- > > v2: > - File alignment was too large, was 8192 should be 512. Reported by > Maarten Lankhorst. > - Added UGA support for graphics > - Use VIDEO_TYPE_EFI instead of hard-coded number. > - Move linelength assignment until after we've assigned depth > - Dynamically fill out AddressOfEntryPoint in tools/build.c > - Don't use magic number for GDT/TSS stuff. Requested by Andi Kleen > - The bzImage may need to be relocated as it may have been loaded at > a high address address by the firmware. This was required to get my > macbook booting because the firmware loaded it at 0x7cxxxxxx, which > triggers this error in decompress_kernel(), > > if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff)) > error("Destination address too large"); > This version seems to boot for me. Is it useful to add 32-bits support though? It seems that only some older versions of OSX use it. I could see if I can revive my mac mini, iirc it has 32-bits efi, or at least used to have.
Do I need to pass anything to add it to efibootmgr?
I tried something like this: echo "args" | efibootmgr -c -l '\vmlinuz.efi' -L 'Native EFI linux boot' -@ - -u -d /dev/sdb
And it boots vmlinuz.efi, but the arguments I passed do not appear to have any effect.
~Maarten
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