Description of problem:

While trying to find a way for a third party open source driver to use the
compat_ioctl structure, the vendor discovered:

> However, after looking at the Red Hat 4 kernel sources, it looks like
> the "newish" compat_ioctl() file op hasn't been back-ported to the
> (current?) Red Hat AS/ES/WS 4 kernel, which looks to be 2.6.9-34.

Chip Coldwell responded that:

He's got us here.  I looked at 2.6.9-34.9.  The compat_sys_ioctl system 
call is there, but the .compat_ioctl field is missing from struct 
file_operations (that merits a bugzilla, IMHO).

I think this is just a matter of adding the field to the struct 
file_operations.  However, it's stuck in the middle, so there are kABI 
repercussions.

This is the bugzilla for that issue.