Messages in this thread | | | From | "H. Peter Anvin" <> | Subject | Re: [PATCH -mm] i386 syscall opcode reordering (pipelining) | Date | Tue, 13 Jun 2006 15:11:20 -0700 (PDT) |
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Followup to: <448F1B97.3070207@linux.intel.com> By author: Arjan van de Ven <arjan@linux.intel.com> In newsgroup: linux.dev.kernel > > Andreas Mohr wrote: > > Hi all, > > > > I'd guess that this version features improved pipeline parallelism, > > since we isolate competing %ebx accesses (_syscall4()) and > > stack push operations (_syscall5()), right? > > is anybody actually EVER using those??? > I would think not....
Probably not. The _syscallN() macros are broken for the general case on any 32-bit architecture, since they can't handle multiregister arguments.
Similarly, a general syscall() function is broken (in the sense that one would have to have syscall-specific code to mangle the arguments) on *some*, but not all, 32-bit architectures, since some architectures have alignment constraints on multiregister arguments, and the syscall number argument throws off that alignment.
-hpa
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