[Buildroot] alsa lib problem

Will Wagner will_wagner at carallon.com
Mon Jan 26 19:12:20 UTC 2009

Hi All,

I have alsa-lib compiling for my arm target however aplay fails to work with the kernel 

ALSA sound/core/pcm_native.c:2587: unknown ioctl = 0x80184132

Decoding this ioctl it is SNDRV_PCM_IOCTL_CHANNEL_INFO defined in asound.h.

The reason it is not working is that the kernel and alsa-lib think that the 
sndrv_pcm_channel_info struct is different sizes.

The definition in asound.h is:

struct sndrv_pcm_channel_info {
	unsigned int channel;
	off_t offset;			/* mmap offset */
	unsigned int first;		/* offset to first sample in bits */
	unsigned int step;		/* samples distance in bits */

The problem is that when compiling linux it thinks off_t is 4 bytes but it appears that 
when compiling alsa-lib it thought it was 8 bytes. I assume this is because something in 
the toolchain on the host PC or the alsa-lib build is wrong and it is picking up a define 
from outside buildroot.

Does this sound possible? How do I establish which definition it is using?


Will Wagner                                     will_wagner at carallon.com
Development Manager                      Office Tel: +44 (0)20 7371 2032
Carallon Ltd, Studio G20, Shepherds Building, Rockley Rd, London W14 0DA

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