Re: [Xen-devel] RFC: 32 bits as smallest atomic size.

[Keir F. <Kei...@cl...>]

On 27 Mar 2005, at 11:56, Keir Fraser wrote:

> I don't think there are that many gcc-isms, apart from use of PACKED 
> (please correct me if I'm wrong). You can always define that to 
> nothing if you need to - I'd hope that no compiler adds padding since 
> all fields should be naturally aligned. I don't see us moving to a 
> model where we define macros on char arrays anytime soon. :-) But 
> perhaps we could include a script to generate such macros from our 
> structure definitions....

Actually this would get round the need to manually determine field 
offsets -- we could get rid of PACKED, let fields fall as they may, and 
then run the headers through gcc to get field offsets for those who 
need them. There are a very few cases where we actually really care 
about two fields being directly adjacent, but I could add annotations 
in the header files and run a script to check that the placement 
constraints are satisfied.

Already the field offset comments are broken in a few places in 
unstable, so perhaps this is a better way to go.

  -- Keir