Re: Why does x86_64 support a SuSE-specific ioctl?

Jeff Garzik (jgarzik@pobox.com)
Sat, 05 Oct 2002 01:04:08 -0400


Andi Kleen wrote:
> Adrian Bunk <bunk@fs.tum.de> writes:
>
>>TIOCGDEV is (as the comment above indicates) in neither 2.4.20-pre9 nor in
>>2.5.40 and I'm wondering why the x86_64 kernel supports a SuSE-specific
>>i386 ioctl?
>
>
> Why not?
>
> I resubmitted the TIOCGDEV patch to Marcelo now, which implements it
> for the console device.
[...]
> diff -urN linux-2.4.18.tmp/include/asm-arm/ioctls.h linux-2.4.18.SuSE/include/asm-arm/ioctls.h
> --- linux-2.4.18.tmp/include/asm-arm/ioctls.h Fri Feb 9 01:32:44 2001
> +++ linux-2.4.18.SuSE/include/asm-arm/ioctls.h Sat May 4 11:37:56 2002
> @@ -49,6 +49,7 @@
> #define TIOCGSID 0x5429 /* Return the session ID of FD */
> #define TIOCGPTN _IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux device) */
> #define TIOCSPTLCK _IOW('T',0x31, int) /* Lock/unlock Pty */
> +#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below /dev/console */
>
> #define FIONCLEX 0x5450 /* these numbers need to be adjusted. */
> #define FIOCLEX 0x5451

"Why not?" is not a very good argument for merging code into the kernel :)

It seems like a good idea to -not- add this ioctl, because
* if 2.4.x and 2.5.x don't have it, there obviously isn't a huge need
for it, so why add one more ioctl we will have to maintain binary
compatibility for
* "real dev" doesn't necessary have meaning in all contexts, IIRC
* viro might have a cow at the use of kdev_t_to_nr... is that required
for compatibility with some existing apps? It seems like you want to
_decompose_ a number into major/minor, to be an interface that
withstands the test of time

-
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