Re: Where is it written?

["H. Peter Anvin" <hpa@zytor.com>]

Followup to:  <20001110192751.A2766@munchkin.spectacle-pond.org>
By author:    Michael Meissner <meissner@spectacle-pond.org>
In newsgroup: linux.dev.kernel
> 
> Generally with ABIs you don't want to mess with it (otherwise you can't be
> guaranteed that a library built by somebody else will be compatible with your
> code, without all sorts of bits in the e_flags field).  It allows multiple
> compilers to be provided that all interoperate (as long as they follow the same
> spec).
> 
> Don't get me wrong -- in my 25 years of compiler hacking, I've never seen an
> ABI that I was completely happy with, including ABI's that I designed myself.
> ABIs by their nature are a compromise.  That particular ABI was short sighted
> in that it wants only 32-bit alignment for doubles, instead of 64-bit alignment
> for instance, and also doesn't align the stack to higher alignment boundaries.
> 

We can mess with the ABI, but it requires a wholescale rev of the
entire system.  We have had such revs before -- each major rev of libc
is one -- but they are incredibly painful.  However, if we find
ourselves in a situation where there are enough reasons to introduce
libc.so.7 then perhaps looking at some revs to the ABI might be in
order -- passing arguments in registers and aligning the stack to 64
bits probably would be the main items.

	-hpa
-- 
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