On Tue, Dec 16, 2008 at 10:34:49PM +0100, Gerd Hoffmann wrote: > Kyle McMartin wrote: > > On Tue, Dec 16, 2008 at 05:48:58PM +0100, Gerd Hoffmann wrote: > >> i.e. the ordering of the splitted argument depends on the os endianness? > >> What is the reason for this? > > > > Eh? The splitting will occur at the C ABI level, not as a result of > > glibc (though, it could be done that way if you really wanted, but then > > you're just moving the wrapper up the chain.) > > Ah, ok. You'll just declare 64bit arg for userspace, gcc splits it into > two 32bit in native byte order, and then the kernel picks up the two > 32bit values and has to reassemble them correctly, right? > > The application-visible API must be compatible to the existing > implementations, i.e. this ... > > pread(long fd, struct iovec *vec, long vlen, off_t pos); > > ... prototype with the unaligned 64bit pos argument (in 32compat case). > > Looks like there is no way around wrapping stuff then for the archs > wanting aligned 64bit values. The only choice we have is to do the > wrap-o-magic in glibc or in the kernel. > > I'd tend handle the wrapping in kernel space then because it is less > confusing and we have to wrap only in case the ABI for $arch requires it. > > Comments? Please do it just the way that Arnd suggested: explicitly pass the upper and lower part of loff_t as separate arguments. It's the most simple approach. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
