RFC: A new MIPS64 ABI

[David Daney]

On 02/14/2011 06:34 PM, Matt Thomas wrote:
>
> On Feb 14, 2011, at 6:26 PM, David Daney wrote:
>
>> On 02/14/2011 06:14 PM, Joe Buck wrote:
>>> On Mon, Feb 14, 2011 at 05:57:13PM -0800, Paul Koning wrote:
>>>> It seems that this proposal would benefit programs that need more than 2 GB but less than 4 GB, and for some reason really don't want 64 bit pointers.
>>>>
>>>> This seems like a microscopically small market segment.  I can't see any sense in such an effort.
>>>
>>> I remember the RHEL hugemem patch being a big deal for lots of their
>>> customers, so a process could address the full 4GB instead of only 3GB
>>> on a 32-bit machine.  If I recall correctly, upstream didn't want it
>>> (get a 64-bit machine!) but lots of paying customers clamored for it.
>>>
>>> (I personally don't have an opinion on whether it's worth bothering with).
>>>
>>
>> Also look at the new x86_64 ABI (See all those X32 psABI messages) that the Intel folks are actively working on.  This proposal is very similar to what they are doing.
>
> untrue.  N32 is closer to the X32 ABI since it is limited to 2GB.
>

It would only be 'untrue' if I had said it was *exactly like* the X32 thing.

Really n32 is, as you note, already quite similar to what X32 is trying 
to do.  My proposal is really for a small improvement to n32 to allow 
doubling the size of the virtual address space to 4GB.

David Daney