Re: [PATCH 2/3] net:ethernet:rmnet:Support for downlink MAPv5 csum offload

[Alex Elder]

On 2/12/21 12:51 PM, Jakub Kicinski wrote:
> On Fri, 12 Feb 2021 08:01:15 -0600 Alex Elder wrote:
> > On 2/11/21 8:04 PM, Jakub Kicinski wrote:
> > > On Fri, 12 Feb 2021 03:05:23 +0530 Sharath Chandra Vurukala wrote:
> > > > +/* MAP CSUM headers */
> > > > +struct rmnet_map_v5_csum_header {
> > > > +	u8  next_hdr:1;
> > > > +	u8  header_type:7;
> > > > +	u8  hw_reserved:5;
> > > > +	u8  priority:1;
> > > > +	u8  hw_reserved_bit:1;
> > > > +	u8  csum_valid_required:1;
> > > > +	__be16 reserved;
> > > > +} __aligned(1);
> > >
> > > Will this work on big endian?
> >
> > Sort of related to this point...
> >
> > I'm sure the response to this will be to add two versions
> > of the definition, surrounded __LITTLE_ENDIAN_BITFIELD
> > and __BIG_ENDIAN_BITFIELD tests.
> >
> > I really find this non-intuitive, and every time I
> > look at it I have to think about it a bit to figure
> > out where the bits actually lie in the word.
> >
> > I know this pattern is used elsewhere in the networking
> > code, but that doesn't make it any easier for me to
> > understand...
> >
> > Can we used mask, defined in host byte order, to
> > specify the positions of these fields?
> >
> > I proposed a change at one time that did this and
> > this *_ENDIAN_BITFIELD thing was used instead.
> >
> > I will gladly implement this change (completely
> > separate from what's being done here), but thought
> > it might be best to see what people think about it
> > before doing that work.
>
> Most definitely agree, please convert.

KS, would you like me to do this to the existing code
first?

I don't think it will take me very long.  If it were
a priority I could probably get it done by the end of
today, but I'd want to ensure the result worked for
the testing you do.

					-Alex