[ipxe-devel] Unable to boot Linux kernel for arm64 architecture

[Mark Rutland]

On Fri, Mar 17, 2017 at 02:14:58PM +0000, Michael Brown wrote:
> On 17/03/17 14:09, Mark Rutland wrote:
> >Is the above definitely an unaligned access? AFAICT, all we know is that
> >it is some kind of synchronous exception, which can encompass a number
> >of other cases.
> 
> The stack trace in the original post included:
> 
> >Synchronous Exception at 0x000000807C5F6B4C
> >snponly.efi loaded at 0x000000807C5EC000
> >
> ><snip>
> >
> >  SP 0x00000007FFE36040  ELR 0x000000807C5F6B4C  SPSR 0x80000309 FPSR 0x0800001A
> > ESR 0x96000021          FAR 0x000000807C61C81E
> >
> >ESR : EC 0x25  IL 0x1  ISS 0x00000021
> >
> >Data abort: Alignment fault

Ah; clearly there is something wrong with my local mail server, as I
only received your reply, and not the original report.

Sorry for the noise, and thanks for the information.

> which I'm assuming must be an unaligned access from within
> snponly.efi, though I'm not very familiar with ARM64's exception
> handling.

That looks likely given the log above.

Both the FAR (the fault address) and the ELR (the PC at the time of the
fault) look close enough to where snponly.efi was loaded.

Otherwise, the ESR tells us the access was a read, but that's about it.

It might be possible to dump SCTLR_ELx to see whether the FW erroneously
set the A bit. Otherwise, it would be interesting to know which platform
this is.

Thanks,
Mark.