[Xorg] The big multiconsole nasty

Jesse Barnes jbarnes at engr.sgi.com
Tue Jul 13 12:25:55 PDT 2004

On Tuesday, July 13, 2004 3:09 pm, Egbert Eich wrote:
> Jesse Barnes writes:
>  > In the arch specific in/out routines you mean?  I see lots of lines like
>  > inb(0x3c8) in various drivers and other code...
> Can you point me to them, please?

There are too many to list.  Just do a 'grep -r inb' in hw/xorg.  Many of the 
inb calls refer to a base, but in some cases (maybe all cases) the IOBase is 
assumed to be global and unique, rather than per-device or per-bus.

>  > in/out is pretty slow already, and is only used at startup time, afaict.
>  >  Most code just does memory reads/writes to register space doesn't it?
> This depends very much on the driver.

Right, that's what I was getting at.  If there are drivers that use in/out as 
their main means of talking to their device, then we'll want to be careful to 
keep them fast.  Otherwise, performance of those routines isn't very 

> Are you sure? I mean I didn't implement it, but I always had the impression
> that the offset values in all the IO code was introduced for that purpose.

Depends on the arch.  ppc has a global IObase, ia64 doesn't use one at all, 
but I think sparc might be able to deal with multiple base (but like I said 
above, I don't think the rest of the code is ready).

> I'll take a look later.

Ok, thanks for looking.


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