I am sorry that I am not clear about the strace..
I am giving here all the details, few of which could be irrelevant.
I have also attached the source code for the device driver (audio_7212.c)
and
the application code (au2.c)
1) The directory entry for the driver looks like this:
crw-rw-r-- 1 0 0 254, 0 Jun24 2000 audio_7212
2) directory entry for the application program:
-rwxr-xr-x 1 0 0 225192 Jun24 2000 au2
When I execute the application program, I see the following:
------------------------------------------------------------
>./au2
Device audio_7212 opened successfully
...
... (Messages printed from au2.c,)
...
write(fp) returned: 9
Closed audio_7212 device.
----------------------------------------------------------
write(fp) returns errono = 9, i.e. EBADF.
This I traced by doing a printk from fs/read_write.c. It comes out
because of the FMODE (mode_f) bit.
I am running this from initrd. I create the initrd on my Linux PC and
download it with the kernel image (arch/arm/boot/Image).
While creating initrd, I do 'mknod /dev/audio_7212 c 254 0' to create the
device driver entry. Then I do a 'chmod 664 /dev/audio_7212' to grant
permissions.
After that I copy au2 to the initrd image.
Thanks....
Umesh Puranik
Russell King - ARM Linux Admin wrote:
> umesh writes:
> > I found out further that this is becasue of the f_mode bit in the
> > 'file' structure. it returns a value of 1 which indicates that there
> > are no read/wrte permissions.
>
> Please give an example of the strace output from running your test
> program.
> _____
> |_____| ------------------------------------------------- ---+---+-
> | | Russell King [EMAIL PROTECTED] --- ---
> | | | | http://www.arm.linux.org.uk/ / / |
> | +-+-+ --- -+-
> / | THE developer of ARM Linux |+| /|\
> / | | | --- |
> +-+-+ ------------------------------------------------- /\\\ |
audio_7212.c
au2.c
