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SubjectRe: procedure for creating new ioctl?
On Mon, 10 Jun 2002, Joseph Cheek wrote:

> hi all,
>
> i'd like to create a new ioctl for use in my kernels [actually i already
> have 8-)] but want to make sure that i follow any established procedure
> for creating it before requesting it be included in the kernel.
> specifically, is there a way to ensure the ioctl number i use isn't in
> use by anyone else? is there a central registry?
>
> so far i've just picked an arbitrary number:
>
> sanfrancisco:/usr/src/linux-2.4.17/include/linux# diff -Naur kd.h{.orig,}
> --- kd.h.orig Mon Jun 10 11:08:22 2002
> +++ kd.h Thu Jun 6 16:00:33 2002
> @@ -177,4 +177,6 @@
> don't reuse for the time being */
> /* note: 0x4B60-0x4B6D, 0x4B70-0x4B72 used above */
>
> +#define KDGETKEYDOWNSTATE 0x4B80 /* read kernel keydown bit */
> +
> #endif /* _LINUX_KD_H */
>
> any tips, pointers appreciated.
>
> joe
>

I use SIOCDEVPRIVATE as the starting value for new ioctls:

/*
* Interface to the private device functions. User API sees this only.
*/
#define CHEK_SEEPROM SIOCDEVPRIVATE + 0x07
#define READ_SEEPROM SIOCDEVPRIVATE + 0x08
#define WRITE_SEEPROM SIOCDEVPRIVATE + 0x09


I've seen this in several drivers. I think this is the way to do it
so there is no interference with other ioctls.

Cheers,
Dick Johnson

Penguin : Linux version 2.4.18 on an i686 machine (797.90 BogoMips).

Windows-2000/Professional isn't.

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