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?
Takashi
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