[syslinux] pxelinux 5.x, 6.x memtest problem

H. Peter Anvin hpa at zytor.com
Fri Jun 28 13:45:13 PDT 2013


On 06/28/2013 04:25 AM, Ady wrote:
> 
> @Wim and @All,
>  FWIW, in 2013-February there still were other additional issues with 
> some kernels, including memory testers, so having a problem to boot 
> memtest(86|86+|other) might or might not be related to the 
> "PXE-stack-smasher" bug.
> 
> For example, in v.4.06, the cfg entry could be:
>  LINUX memtest
> 
> and it would work OK, but if the entry was:
>  COM32 linux.c32
>  APPEND memtest
> 
> it could / would fail, even using SYSLINUX (or PXELINUX). This 
> behavior with linux.c32 seemed to indicate that there were already 
> potential problems ahead in Syslinux 5.xx with certain kernels.
> 
> Also, as a remainder, memtest is for BIOS only (AFAIK, at least 
> current versions).
> 
> So, if someone was having problems with memtest before, I would 
> suggest trying again with the latest Syslinux build(s), booting with 
> SYSLINUX and with PXELINUX. Comparing the results might help clarify 
> whether the problem is actually related to the "PXE-stack-smasher" 
> bug, or to something else (which might have been already solved in 
> the last few months / days / hours).
> 

This problem is understood, it just isn't entirely trivial to fix.  The
problem is that memtest is an "ancient" kernel which has to be loaded at
a fixed address, but the PXE stack also wants to use the same address.
This causes issues if one also wants sane error behavior.

Incidentally, a member of my team at Intel did a patch to update this
bit of memtest; I'm should check to see if it went upstream yet.

	-hpa




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