Re: [RFC] Introduce __ARCH_WANT_SYS_SYSFS

[Will Newton]

 On Tue, Apr 22, 2008 at 4:38 PM, Kyle McMartin <kyle@xxxxxxxxxxx> wrote:
> On Tue, Apr 22, 2008 at 04:34:03PM +0100, Will Newton wrote:
>  > On Tue, Apr 22, 2008 at 4:24 PM, Kyle McMartin <kyle@xxxxxxxxxxx> wrote:
>  > > On Tue, Apr 22, 2008 at 04:16:17PM +0100, Will Newton wrote:
>  > >  > It can be done with Kconfig. Whether it should be or not depends on
>  > >  > your point of view, hence RFC. Currently __ARCH_WANT macros is the way
>  > >  > syscalls are enabled and disabled across architectures. If there's
>  > >  > consensus that it should be done via Kconfig that could certainly be
>  > >  > implmented, but that's a different patch.
>  > >  >
>  > >
>  > >  It's currently done in unistd.h for hysterical raisins. All new
>  > >  conditional syscalls have been done in Kconfig.
>  >
>  > Do you have a syscall in mind that does this in the correct way?
>  >
>
>  epoll is the most immediate example at hand, since it touches
>  fs/compat.c similarly to how you would be touching fs/filesystem.c, and
>  touches kernel/sys_ni.c and init/Kconfig in much the same way.

I implemented the approach you suggested - Kconfig symbol and
cond_syscall definition. I think I actually like the previous approach
better:

1. The arch Kconfig files are quite non-uniform compared to unistd.h
so the definitions wind up at different places in the file which is a
bit messy.
2. Changes to Kconfig may cause churn in defconfigs perhaps?
3. There is more churn in arch Kconfig than unistd.h so getting a
cross arch patch applied is likely to be more difficult.
4. The patch is about 4 times as many lines.

What do you think?