On 2005-03-10 18:22:56 +0000, Nikita Schmidt wrote: > I'm pretty much convinced it's a kernel bug. Firstly, to follow your > logic: > > > gnome-volume-control gives warnings: > > > > ** (gnome-volume-control:5579): WARNING **: Error getting device (7) > > volume: Operation not permitted > > > > ** (gnome-volume-control:5579): WARNING **: Error getting recording device > > (7) volume: Operation not permitted > > > > but works without any problem. So, this is not a bug in the kernel. > > tkmixer works on all kernels except some versions of powerpc, so this is > not a bug in tkmixer, right?
No, this doesn't mean anything. I don't think that the PowerPC kernel has done anything wrong. > But the real reasons why I think it's a kernel bug are below. > > 1. The ioctl which returns EPERM is a request to get the value of mixer > control no. 7 (Microphone). Previous three similar ioctls for controls 0 > (Master volume), 5 (Speaker) and 6 (Line) have all succeeded, as shown by > strace. I see no logic in that reading some mixer elements is permitted > and reading others is not. Because there's no microphone? > 2. Permission checks are usually done at device openinig time, not at > ioctl time. One has more control on what can be read or not at ioctl time. This is just like file vs file system permissions. > 3. EPERM's code is 1, which means that the mixer ioctl handler in the > kernel returns -1, which is then translated to an error condition with > errno = -(-1) = 1 = EPERM. I think that -1 is returned by mistake; if > EPERM had a different error code, the code returned would still be 1, and > not EPERM's. Well, I don't know about the error codes (perhaps EPERM isn't the right one). But I don't see why the kernel shouldn't return an error for something that doesn't exist. > Of course, I could equip tkxmier with a workaround similar to the one in > gnome-volume-control, or forgo error checking altogether, like most other > mixers that "work" on powerpc do, and let the real bug go unnoticed. > But before that, I'd still like to bounce this off PowerPC kernel/sound > driver developers, or even look into this myself if you give me precise > details about the kernel and platform: driver type (OSS or ALSA), sound > device (AWACS/Burgundy/etc.), kernel configuration, gcc version, and the > kernel-image package used (I couldn't find kernel-image-2.6.9-powerpc in > Debian archive). It might even be a result of miscompilation by gcc. I'm using the kernel-image-2.6.10-powerpc package. If you need more information, could you tell me precisely where I should look? In case this can be useful: ay:~> lsmod|grep sound dmasound_pmac 94820 1 dmasound_core 22096 2 dmasound_pmac soundcore 11780 3 snd,dmasound_core -- Vincent Lefèvre <[EMAIL PROTECTED]> - Web: <http://www.vinc17.org/> 100% accessible validated (X)HTML - Blog: <http://www.vinc17.org/blog/> Work: CR INRIA - computer arithmetic / SPACES project at LORIA -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
