Re: [Qemu-devel] [PATCH] pcnet32 driver change, please test

[Paul Brook <paul@codesourcery.com>]

> : I find this curious...  C99 (6.7.2.1) says "the allocation order of
> : bit-fields within a unit (high-order to low-order or low-order to
> : high-order) is implementation defined".  I can't see any requirement
> : for this, so is it just convention that bitfields on big endian systems
> : start from the most significant bit, and those on little endian systems
> : start from the least significant bit?  (My thinking is that endianness
> : usually refers to byte ordering and not so much bit ordering.)
>
> This is a convention that goes back a very long ways.  It was this way
> in the mid 1980's, and has remained true through today.  I've
> personally observed this to be the case on many different MIPS
> compilers, ARM compilers and SPARC compilers over the years.

I'm fairly sure I've seen targets that use other bitfield orderings, though I 
can't remember offhand what they were.

Paul