🚀 go-pugleaf

Paul Repper wrote:
[...]
> 16k byte pages of memory are allocated in which structures will be stored.
> While accessing structures within the allocated pages, I receive a
> "BUS fault (alignment error)".  The fault seems to occur anytime the
> structure is aligned on an odd byte.  We are also unable to access the
> bit fields even if they are aligned on an even address.
> 
> There are two situations which we believe contribute to the problems being
> experienced:
>   1.  We cannot globally pack structures on 1-byte alignments.
>       We can pack individual structures i.e.
>         typedef struct x {...} __attribute__((packed)) X;
>       but this does not seem to cure the problem either.
>   2.  We cannot access structures or bit-fields aligned on odd- or
>       even-bytes.

SPARC processors cannot access 16- and 32-bit objects at odd addresses.
I believe that all memory objects larger than a byte must be on an
even 4-byte boundary in fact, making 16-bit values of limited use.
Structure packing for *all* SPARC compilers will, of course, be
constrained to these requirements.

You have one of two ways to solve this problem: if the "memory footprint"
of the structure *must* be identical to the x86 version, you can pack/
unpack the structures into "native" SPARC structures before/after using.
If the memory footprint is not important, just use a structure with the
same C language elements as the x86 version, and let the compiler place
the bits where the SPARC wants them.


-- 
   Wes Peters	| Yes I am a pirate, two hundred years too late
    Softweyr 	| The cannons don't thunder, there's nothing to plunder
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 wes@intele.net	|					Jimmy Buffet