Re: [Lksctp-developers] 32-bit applications on 64-bit kernel (sctp-get{l,p}addrs() )

[Sridhar S. <sr...@us...>]

On Mon, 2005-09-26 at 23:41 +0200, Ivan Skytte J=C3=B8rgensen wrote:
> On Sunday 25 September 2005 21:36, Ivan Skytte J=C3=B8rgensen wrote:
> > On Tuesday 20 September 2005 00:11, Sridhar Samudrala wrote:
> > [...]
> >
> > > 2. Make all the structures as packed so that the sizes are independ=
ent
> > >    of the architecture and keep the kernel code simple, but break t=
he
> > >    binary compatibility.
> > >
> > > Is it worth maintaining binary compatiblity and have some messy
> > > compatibility code in the kernel?
> > > Also there seems to be atleast one structure(sctp_paddrparams) whic=
h
> > > needs to be updated to the latest draft.
> > >
> > > I would prefer the 2nd option and let the apps rebuild using the ne=
w
> > > header file when they would like to run on newer kernels.
> >
> > I am preparing a patch that fixes the structure sizes and only breaks
> > 64-bit programs where needed. Expect something the next week.
> >
> > I followed the discussion in tsvwg mailing list. My interpretation of=
 the
> > few answers is that this is a "quality of implementation issue" and t=
hat
> > padding fields are allowed but won't get into the RFC because it is a=
n
> > implementation issue.
>=20
> __attribute((packed)) patches attached.
>=20
> patch summary:
>   - sctp_sndrcvinfo: Explicit 16-bit padding inserted
>   - sctp_paddr_change: __attribute__ ((packed))
>   - sctp_remote_error: Explicit 16-bit padding inserted
>   - sctp_setpeerprim:  __attribute__ ((packed))
>   - sctp_prim:  __attribute__ ((packed))
>   - sctp_paddrparams: Explicit 16-bit padding inserted. __attribute__=20
> ((packed))
>   - sctp_paddrinfo: __attribute__ ((packed))
>=20
> 32-bit programs should remain unaffected. 64-bit programs will break if=
 using=20
> sctp_paddr_change, sctp_setpeerprim, sctp_prim, sctp_paddrparams or=20
> sctp_paddrinfo
> . I did not add the aligned(4) attribute as it is not strictly needed.

With aligned(4), i think you don't need to add any padding.
On ppc64, by adding
   __attribute__((packed, aligned(4)))
to sctp_paddr_change, sctp_remote_error, sctp_setpeerprim, sctp_prim.
sctp_paddrparams and sctp_paddrinfo

i was able to get 32/64 and 64/64 to work and also

old 32-bit apps on intel 32.

Could you try this on x86-64? If you prefer, i can send you the patch.

Thanks
Sridhar

>=20
> Tested with 32/64 and 64/64 on x86_64
>=20
> With the sctp-get{l,p}addrs() patch, and this patch, and Sridhar's msg_=
flag=20
> patch, the whole test suite passes.
>=20
> I have not tested with 32-bit programs using the "old" lksctp-1.0.3 bec=
ause=20
> there is know breakage in sctp_get{l,p}addrs()