Re: [PATCH] drivers/char/mem.c: Add /dev/ioports, supporting 16-bit and 32-bit ports

H. Peter Anvin
2014-05-09T21:20:45Z

On 05/09/2014 02:12 PM, Arnd Bergmann wrote:
>
>> However, if we're going to have these devices I'm wondering if having
>> /dev/portw and /dev/portl (or something like that) might not make sense,
>> rather than requiring a system call per transaction.
>
> Actually the behavior of /dev/port for >1 byte writes seems questionable
> already: There are very few devices on which writing to consecutive
> port numbers makes sense. Normally you just want to write a series
> of bytes (or 16/32 bit words) into the same port number instead,
> as the outsb()/outsw()/outsl() functions do.
>

Indeed. I missed the detail that it increments the port index; it is
virtually guaranteed to be bogus.

-hpa