* H. Peter Anvin <[EMAIL PROTECTED]> wrote: >> Why not just pin down the current ABI that there's 6 syscall >> parameters _and not more_? > > Because we have already violated it. There are system calls that need > more than 6 arguments: we need *a* convention. Worse, we're not > actually talking 6 *arguments*, we're talking 6 *words*; on 32-bit > platforms a single argument can occupy two words.
i think you are at least partly wrong here. Multiplexing/demultiplexing can go on infinitely - for example sys_write(fd, size, buf) can be thought of as a function call that passes in fd, size and a variable number of arguments of the data to be written. in that sense capping function arguments at 6 is _sensible_ because it prefers _simple_ interfaces. When i wrote syslets i did a syscall number of arguments histogram: #args #syscalls ----------------- 0 22 1 51 2 83 3 85 4 40 5 23 6 8 Fortunately what we see today is that 80% of all syscalls have 4 or less parameters. (yes, there are a few 6-parameter syscalls that arguably hurt, but still, it's the exception not the rule) this histogram shows a healthy bell curve which is _not_ limited by the arguments limit of 6, but by common sense! If the 6-arguments limit was a problem then we'd see a pile-up of 6-param syscalls. so i believe you should start thinking about lots-of-arguments syscalls as an exception not as something that needs to fit into some generic ABI. (Especially as most schemes that were supposed to handle this problem would hurt the sane 4-parameter (or less) syscall case too.) Ingo - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/