[ipxe-devel] [1c838002] memtest86+.bin vs. memtest86.bin?

[Michael Brown]

On Friday 17 Aug 2012 11:25:05 Ivan Shmakov wrote:
>  > The advantage of using memtest.0 is that you can exit back to iPXE
>  > without rebooting,
> 
> 	This didn't work for me — hitting ESC in memtest86+.0
> 	(f9d3679f3770, running under QEMU/KVM) results in:
> 
> Could not boot: Error 0x00000002 (http://ipxe.org/00000002)

That's expected behaviour.  Exit codes from memtest.0 are:

  0 : success
  1 : at least one failure was observed
  2 : a complete test was not performed

>  >   chain http://boot.ipxe.org/memtest.0 passes=1 && goto passed || goto
>  >   failed
> 
> 	ACK, thanks.
> 
> 	Do I understand it correctly that ‘chain’ implements some part
> 	of the PXE protocol that allows it to pass “command line” to the
> 	image loaded?

Yes.

> 	While Memtest86+/PXE binary is a worthwhile addition, I'm still
> 	interested in what exactly are the iPXE criteria the “stock”
> 	Memtest86+ binary fails to meet?  I'd like to try iPXE to
> 	bootstrap other systems (such as FreeBSD), and it'd probably
> 	save me some time if I'd know where to look should it fail.

The motivation for creating memtest.0 was that the other memtest formats often 
don't work, for reasons that can't easily be fixed.  For example, the default 
memtest.bin is an old-format zImage, which requires part of its code to be 
loaded at 0x90000.  On many systems, this area of memory will already be 
occupied when loading via PXE.

Michael