Re: RFD: x32 ABI system call numbers

[H. Peter Anvin]

On 09/03/2011 10:16 AM, Valdis.Kletnieks@xxxxxx wrote:
> > The complexity of changing that would be enormous.
>
> Oh, I know changing the x86-32 ABI is impossible - I meant changing the
> decision to emulate that ABI (as opposed to emulating the x86-64 ABI, or a
> variant thereof, or something else).  Or are we already commited to that
> route, even if we're still trying to figure out what syscalls to include?

About ioctl in particular, the ABI has dependencies into almost every 
single driver in the Linux kernel.  It is hard-coded in the kernel that 
there are two paths -- native and compat.  Since pointers are going to 
be 4 bytes, it means we have to use the compat path.

We may be able to cheat a little bit since we encode the argument sizes 
in the ioctl numbers; this solves the case of PPGETTIME/PPSETTIME for 
example (in fact, this ioctl looks currently broken in compat mode!) 
However, at some point the sheer number of data types that can be 
consumed by ioctl is a real concern, so changing the ones we really care 
about -- like timespec/timeval -- while leaving the rest intact so we 
can use the compat path as a general rule would be highly useful.

	-hpa

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