Re: Bug#609371: linux-image-2.6.37-trunk-sparc64: module scsi_mod:

[Mathieu Desnoyers <mathieu.desnoyers@efficios.com>]

* Sam Ravnborg (sam@ravnborg.org) wrote:
> > 
> > I still wonder how a 32-bit system can generate an unaligned access trap for an
> > access to a 64-bit variable aligned on 32-bit, given that there is, by
> > definition, no 64-bit memory accesses available on the architecture ?
> 
> From the SPARC V8 manual (this is the 32 bit version of SPARC):
> 
>     Load/Store Instructions
> 
>     ...
>     Integer load and store instructions support byte (8-bit), halfword (16-bit), word
>     (32-bit), and doubleword (64-bit) accesses.
>     ...
> 
>     Alignment Restrictions
> 
>     Halfword accesses must be aligned on a 2-byte boundary, word accesses (which
>     include instruction fetches) must be aligned on a 4-byte boundary, and doubleword
>     accesses must be aligned on an 8-byte boundary. An improperly aligned
>     address causes a load or store instruction to generate a mem_address_not_aligned
>     trap.

Ah! There is always an odd case ;) Thanks!

Mathieu


-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com