* Re: [PATCH net-next v4 04/15] mctp: Add sockaddr_mctp to uapi
2021-10-14 18:34 ` [PATCH net-next v4 04/15] mctp: Add sockaddr_mctp to uapi Eugene Syromiatnikov
@ 2021-10-15 1:18 ` Jeremy Kerr
2021-10-15 6:27 ` Geert Uytterhoeven
1 sibling, 0 replies; 3+ messages in thread
From: Jeremy Kerr @ 2021-10-15 1:18 UTC (permalink / raw)
To: Eugene Syromiatnikov
Cc: netdev, Matt Johnston, Andrew Jeffery, Jakub Kicinski,
David S. Miller, linux-m68k
Hi Eugene,
Thanks for taking a look at these!
> > +typedef __u8 mctp_eid_t;
> > +
> > +struct mctp_addr {
> > + mctp_eid_t s_addr;
> > +};
> > +
> > struct sockaddr_mctp {
> > + unsigned short int smctp_family;
>
> This gap makes the size of struct sockaddr_mctp 2 bytes less at least
> on m68k, are you fine with that?
Yep, that's OK from the protocol implementation side; this layout better
matches the "hierarchy" of the MCTP addressing. If we go for optimal
packing, the order of the members makes somewhat less sense. We could
add padding members, but I'm not sure that's worth it...
I noticed a few other protocol implementations doing similar things, so
assume it isn't an issue - it's all arch-specific ABI anyway, right?
> > + int smctp_network;
> > + struct mctp_addr smctp_addr;
> > + __u8 smctp_type;
> > + __u8 smctp_tag;
> > };
Cheers,
Jeremy
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH net-next v4 04/15] mctp: Add sockaddr_mctp to uapi
2021-10-14 18:34 ` [PATCH net-next v4 04/15] mctp: Add sockaddr_mctp to uapi Eugene Syromiatnikov
2021-10-15 1:18 ` Jeremy Kerr
@ 2021-10-15 6:27 ` Geert Uytterhoeven
1 sibling, 0 replies; 3+ messages in thread
From: Geert Uytterhoeven @ 2021-10-15 6:27 UTC (permalink / raw)
To: Eugene Syromiatnikov
Cc: Jeremy Kerr, netdev, Matt Johnston, Andrew Jeffery,
Jakub Kicinski, David S. Miller, linux-m68k
On Fri, Oct 15, 2021 at 12:32 AM Eugene Syromiatnikov <esyr@redhat.com> wrote:
> On Thu, Jul 29, 2021 at 10:20:42AM +0800, Jeremy Kerr wrote:
> > This change introduces the user-visible MCTP header, containing the
> > protocol-specific addressing definitions.
>
> [...]
>
> > --- a/include/uapi/linux/mctp.h
> > +++ b/include/uapi/linux/mctp.h
> > @@ -9,7 +9,28 @@
> > #ifndef __UAPI_MCTP_H
> > #define __UAPI_MCTP_H
> >
> > +#include <linux/types.h>
> > +
> > +typedef __u8 mctp_eid_t;
> > +
> > +struct mctp_addr {
> > + mctp_eid_t s_addr;
> > +};
> > +
> > struct sockaddr_mctp {
> > + unsigned short int smctp_family;
>
> This gap makes the size of struct sockaddr_mctp 2 bytes less at least
> on m68k, are you fine with that?
>
> > + int smctp_network;
> > + struct mctp_addr smctp_addr;
> > + __u8 smctp_type;
> > + __u8 smctp_tag;
And it may be wise to add 1 byte of explicit padding here?
Or is there a good reason not to do so?
> > };
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
^ permalink raw reply [flat|nested] 3+ messages in thread