[ipxe-devel] iMac 2007 silently fails booting kernel

[Linus Lüssing]

On Sat, Jan 16, 2016 at 01:15:20PM +0000, Michael Brown wrote:
> On 16/01/16 12:35, Linus Lüssing wrote:
> > I also extracted the 64-bit ELF vmlinux from the vmlinuz (bzimage)
> > and tried booting that. However this gave me an "Exec format error"
> > again, apparently.
> >
> > With UEFI and an Intel Core 2 Duo I should be able to chainload
> > into a 64-bit ELF from the 64-bit ipxe.efi, shouldn't I? Or am I
> > missing something obvious?
> 
> No; on a UEFI platform you can load only iPXE scripts and EFI 
> executables.  You can't directly load an ELF binary.

Ah, okay. But technically, theoretically it would be possible to
implement an iPXE EFI to boot into an ELF kernel, wouldn't it? I
mean, even an EFI kernel will be able and need to run ELFs at some
point.

Anyways, the kernel I have seems to have CONFIG_EFI_STUB=y set, so
it should be suitable to be chainloaded from an iPXE EFI, even if
"$ file vmlinux" says it's an ELF, right?

(though from the brief wiki scaning I'm not quite sure what
EFI_STUB does, yet. Especially don't know whether extracting the
vmlinux from the provided vmlinuz kind of breaks EFI_STUB for
vmlinux bc. of specific entry point addresses or something like
that, don't know - that would explain the "Exec format error" for
the extracted vmlinux and why there's no such error for the
original vmlinuz)


Will try the compile time option in a second, thanks!