Hi Yair,
This makes perfect sense. Will appear in the hg server soon.
Best regards,
Hannu
---------
Yair K. wrote:
> Hi,
>
> I discovered something of interest: A 32bit ossmix on a 64bit Linux system
> will fail ("Error: OSS version 3.9 or later is required"). I believe what
> happens is that since 2.6.11 64bit Linux expects drivers to declare a
> compat_ioctl function pointer in order to get 32bit ioctls (
> http://lwn.net/Articles/119652/ ). The compact_ioctl function does the
> neccesary translation of data structures back and forth while calling the
> real ioctl. Since the kernel still has OSS, it lets most SNDCTL_DSP_* calls
> through anyway (see fs/compat_ioctl.c), but the new mixer API calls get
> something like "ioctl32(ossmix32:3339): Unknown cmd fd(3)
> cmd(c470580a){t:'X';sz:1136} arg(f3cde50c) on /dev/mixer" in dmesg...
>
> The attached patch declares the compat_ioctl and unlocked_ioctl (on that in
> a moment) members, so that 32bit mixer clients will work. There are several
> important notes per the LWN article:
> A. unlocked_ioctl is a new member. It's a regular ioctl, except:
> 1. No inode member (oss_cdev_ioctl didn't use it anyway).
> 2. No giant lock before the ioctl (OSS has its own locking. It seems
> to work fine, but I haven't tested it heavily).
> 3. The kernel will call unlocked_ioctl instead of ioctl if it exists
> compat_ioctl has 1&2 properties as well, so OSS might as well use
> unlocked too..
> B. I don't think OSS API passes any structure which are incompatible
> between 32 and 64bit, so I just had compat_ioctl call oss_cdev_ioctl. All
> structures use fields with the same meaning across 32bit/64bit systems, and I
> don't see any padding issues, but I could have missed something...
>
> Yours,
> Yair K.
>
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>
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