[U-Boot] [PATCH] 8313erdb: Set guarded bit on BAT that covers the end of the address space.

[Mike Frysinger <vapier@gentoo.org>]

On Tuesday 17 March 2009 13:09:31 Scott Wood wrote:
> This board currently sets DBAT6 to cover all of the final 256MiB of
> address space; however, not all of this space is covered by a device.  In
> particular, flash sits at 0xfe000000-0xfe7fffff, and nothing is mapped
> at the far end of the address space.
>
> In zlib, there is a loop that references p[-1] if p is non-NULL.  Under
> some circumstances, this leads to the CPU speculatively loading from
> 0xfffffff8 if p is NULL.  This leads to a machine check.

isnt that a compiler generating bad code then ?  if C code is doing ptr 
checks, the compiler should make sure that pointer is not dereferenced at all 
if the hardware cannot suffer the consequences, even speculatively.
-mike
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