Re: [patch][rfa]: SID mapper component - wordsize

[Dave Brolley <brolley@redhat.com>]

Frank Ch. Eigler wrote:

>brolley wrote:
>
>  
>
>>[...] The specification
>>[4*1000-1010]
>>should allow access to the range 4000-4043, however, the upper bound
>>is simply being multiplied by the wordsize, resulting in an upper
>>bound of 4040.
>>    
>>
>
>Actually, addresses in the mapper specs are inclusive, not exclusive.
>That's why one often sees ranges ending with ...ffff.  Plain raw
>scaling such inclusive limits doesn't make sense though, so a special
>case calculation like yours would make sense.  However, care should be
>taken not to confuse exclusive vs inclusive bounds.
>
Right. That's precisely what the patch does. It computes the intended 
inclusive bounds.

>>If the mapper is accessed using wordsized elements, the problem goes
>>unnoticed, since the mapper does not check the ending address of the
>>range being accessed.
>>    
>>
>
>That's a peculiar other bug.  To be consistent with the byte-oriented
>addressing across sid::bus, the size of the access would need to be
>included in the checks.
>  
>
That's a separate bug (wasn't sure if it was intentional or not) and an 
exercise for someone's copious spare time :-)

Dave