On Sat, 16 Jan 2016 09:51:29 +0100,
Takashi Iwai wrote:
>
> On Sat, 16 Jan 2016 00:14:01 +0100,
> Andrew Morton wrote:
> >
> > On Sat, 16 Jan 2016 10:00:47 +1100 Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> wrote:
> >
> > > Hi Andrew,
> > > > +#define SNDRV_COMPRESS_GET_CODEC_CAPS _IOWR('C', 0x11, struct snd_compr_caps)
> > > > #define SNDRV_COMPRESS_SET_PARAMS _IOW('C', 0x12, struct snd_compr_params)
> > > > #define SNDRV_COMPRESS_GET_PARAMS _IOR('C', 0x13, struct snd_codec)
> > > > #define SNDRV_COMPRESS_SET_METADATA _IOW('C', 0x14,\
> > > >
> > > > then it compiles OK. So there's something special about `struct
> > > > snd_compr_codec_caps' which is confusing the compiler.
> > >
> > > Its very big (hint, I think it is bigger than 1 << 13).
> >
> > ah-hah.
> >
> > sizeof(struct snd_compr_codec_caps) is 11144 on x86_64
> > allyesconfig, but x86_64 uses (1<<14), not (1<<13) - x86_64 has more
> > space in the ioctl payload.
> >
> >
> > So. Sound guys: your struct snd_compr_codec_caps is too large for
> > powerpc ioctls.
>
> Ouch, this was what I was concerned. I thought we did calculate it at
> the time writing API, alas, we failed. We need to do math drills
> again...
>
> There are a few ways to fix this, but all are not comfortable.
>
> A. Disable compress API for powerpc.
>
> B. Disable this ioctl for powerpc and keep it for others while
> providing yet a new ioctl for the similar functionality.
>
> B1. Pass the same struct via a pointer: this needs a special
> compat_ioctl handling
> B2. Reduce the size of struct snd_compr_codec_caps, e.g. set
> MAX_NUM_CODEC_DESCRIPTORS to 16.
>
> C. What else?
Vinod, what's your take?
Takashi
--
To unsubscribe from this list: send the line "unsubscribe linux-next" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
