Re: X32 psABI status

[H.J. Lu]

On Sun, Feb 13, 2011 at 3:39 PM, Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> wrote:
>> a. the int $0x80 instruction is much slower than syscall.  An actual
>>    i386 process can use the syscall instruction which is disambiguated
>>    by the CPU based on mode, but an x32 process is in the same CPU mode
>>    as a normal 64-bit process.
>
> So set a flag, whoopee
>
>> b. 64-bit arguments have to be split between two registers for the
>>    i386 entry points, requiring user-space stubs.
>
> Diddums. Given you've yet to explain why everyone desperately needs this
> extra interface why do we care ?
>
>> All in all, the cost of an extra system call table is quite modest.
>
> And the cost of not doing it is a gloriously wonderful zero. Yo've still
> not explained the justification or what large number of apps are going to
> use it.
>
> It's a simple question - why do we care, why do we want the overhead and
> the hassle, what do users get in return ?
>

The real question is if we need to use ia32.  If the answer is yes, then
x32 provides the benefit of ia32 with register extended to 64bit plus 8
more registers as well as IP relative address.

-- 
H.J.
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