On Fri, Dec 07, 2007 at 05:20:18AM -0500, Dan Williams wrote:
> On Thu, 2007-12-06 at 11:11 -0800, Jean Tourrilhes wrote:
> > On Thu, Dec 06, 2007 at 06:28:39AM -0500, Dan Williams wrote:
> > > See the previous thread about fixing the ap_scan mess. I think Jean's
> > > correct in asserting that we need more bits for scan capability.
> > >
> > > This patch introduces scan capability bits for WEXT; hopefully cfg80211
> > > can also pick up equivalent functionality. Capability bits are provided
> > > for all the current options that may be passed to drivers in the
> > > iw_scan_req structure. It can be assumed that if the driver reports the
> > > scan capability, that the driver respects the options specified in the
> > > iw_scan_req structure when performing the scan.
> > >
> > > Clients can use logic like (cribbed from wpa_supplicant's driver_wext.c)
> > > this to figure out whether or not the capability bits are supported:
> > >
> > > struct iwreq iwr;
> > > struct iw_range *range;
> > >
> > > <set up iwr/range for request>
> > >
> > > if (ioctl(drv->ioctl_sock, SIOCGIWRANGE, &iwr) == 0) {
> > > u8 minlen = ((char *) &range->scan_capa) - (char *) range + sizeof(range->scan_capa);
> > >
> > > if (iwr.u.data.length >= minlen) {
> > > /* SCAN_CAPA is supported */
> > > }
> > > }
> > >
> > > Jean; what do you think?
> >
> > Actually, I like your new proposal. I told you there was a
> > gotcha, you need to add some padding to not screw up userspace. Note
> > that we have already some padding in that structure (look at 'old_*'),
> > so it's not the first time we do that.
> > Basically, it should look like the patch below...
> >
> > Regards,
> >
> > Jean
> >
> > Signed-off-by: Jean Tourrilhes <jt@xxxxxxxxxx>
> >
> > --- linux/include/linux/wireless.d1.h 2007-12-06 11:04:16.000000000 -0800
> > +++ linux/include/linux/wireless.h 2007-12-06 11:06:26.000000000 -0800
> > @@ -1040,6 +1040,16 @@ struct iw_range
> > * because each entry contain its channel index */
> >
> > __u32 enc_capa; /* IW_ENC_CAPA_* bit field */
> > +
> > + /* Do *NOT* use those fields, they are just used as padding to get
> > + * proper alignement with user space */
> > + __s32 min_pms;
> > + __s32 max_pms;
> > + __u16 pms_flags;
> > + __s32 modul_capa;
> > + __u32 bitrate_capa;
> > +
> > + __u32 scan_capa; /* IW_SCAN_CAPA_* bit field */
> > };
>
> Can you explain a bit more about this patch?
Those fields are defined and used in userspace, please check
wireless.21.h in Wireless Tools.
> Also, if nobody is
> supposed to use these fields, shouldn't their names be 'reserved' or
> something like that?
Yeah, you could do that. It does not matter eather way. Using
the same name as userspace has the advantage of making consistency
check easier.
> Thanks,
> Dan
Regards,
Jean
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