x32 psABI draft version 0.2

[H. Peter Anvin]

On 02/17/2011 10:06 AM, Jakub Jelinek wrote:
> On Thu, Feb 17, 2011 at 04:44:53PM +0100, Jan Hubicka wrote:
>>>> According to Mozilla folks however REL+RELA scheme used by EABI leads
>>>> to significandly smaller libxul.so size
>>>>
>>>> According to http://glandium.org/blog/?p=1177 the difference is about 4-5MB
>>>> (out of approximately 20-30MB shared lib)
>>>
>>> This is orthogonal to x32 psABI.
>>
>> Understood.  I am just pointing out that x86-64 Mozilla suffers from startup
>> problems (extra 5MB of disk read needed) compared to both x86 and ARM EABI
>> because x86-64 ABI is RELA only. If x86-64 ABI was REL+RELA like EABI is, we
>> would not have this problem here.
> 
> libxul.so has < 200000 relocs, so 5MB is total size of .rela section in
> 64-bit ELF, you don't magically save those 5MB by using REL.  You save
> just 1.5MB.  And for x32 we'd be talking about 2.5MB for RELA vs. 1.6MB for
> REL.  There might be better ways how to get the numbers down.
> 

The size is, of course, half of that for the x32 ABI in the first place.

	-hpa