Re: why is asm-parisc/ioctl.h subtly different from asm-generic/ioctl.h?

From: Kyle McMartin
Date: Sat Feb 24 2007 - 13:45:47 EST


On Sat, Feb 24, 2007 at 05:34:15AM -0500, Robert P. J. Day wrote:
>
> just noticed that parisc's ioctl.h file, rather than simply
> including asm-generic/ioctl.h, has its own copy whose sole
> (meaningful) difference from the generic one is:
>
> $ diff include/{asm-generic,asm-parisc}/ioctl.h
> ...
> 41,42c54,55
> < #define _IOC_WRITE 1U
> < #define _IOC_READ 2U
> ---
> > #define _IOC_WRITE 2U
> > #define _IOC_READ 1U
>
> so parisc is identical except that it switches the meaning of the
> direction field? is there a reason for this? just curious.
>

HP-UX compatibility.

#define IOC_OUT 0x40000000
#define IOC_IN (int)0x80000000

PS: It would be wise to ask questions on the pertinent mailing lists...

--Kyle
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