[Xorg] The big multiconsole nasty

Alan Cox alan at lxorguk.ukuu.org.uk
Mon Jul 12 13:00:31 PDT 2004

On Llu, 2004-07-12 at 14:51, Jesse Barnes wrote:
> In the arch specific in/out routines you mean?  I see lots of lines like 
> inb(0x3c8) in various drivers and other code...

There are some fun problems with the vga module and devices that can
relocate their vga registers too as with the SiS driver (and some good
discussion in the driver code)

> 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?

In iopl(3) mode out and in are pretty fast (obviously not as fast as 
posted PCI mmio).

> Yeah, I'm looking at the ia64 stuff, it's still missing the necessary support.  
> It looks like ppc is still limited to doing legacy I/O (like the above inb) 
> to one bus.

Same with the IBM x440 if you use legacy addressing

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