On Sun, Feb 13, 2011 at 3:39 PM, Alan Cox <a...@lxorguk.ukuu.org.uk> 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.
