X-video-server [Open-graphics]

[James Richard Tyrer]

Hamish wrote:
> On Saturday 01 July 2006 10:37, Dieter wrote:
>>> no, itآ�s not the problem to have Eth ports on the PC side, as you notice
>>> yourself _Dieter_ even low-end PC privide one port.
>>> Rather, a chip on the PCآ�s mobo which route the PCI signal through
>>> Ethernet.
>>> (and on the monitor g-card, the contrary, though it could be not
>>> necessarly to bother with a PCI slot, as you suggest)
>> Oh!  I think I *finally* understand what you want.  A PCI slot extender
>> that uses Ethernet for the link.  Interesting idea.  I don't know of such a
>> device.  Anyone?  The closest thing to this that I know of is a device for
>> adding more PCI slots or adding PCI slots to laptops.  It looks like the
>> cable is limited to 1.5 meters.  It is also expensive.  For most purposes
>> one might as well buy an additional computer instead.
>>
>> http://www.mycableshop.com/sku/PCI-P7T.htm
>>
>> It might be that the PCI bus has timing/latency requirements that prevent
>> a remote slot over a long cable?
>>
> 
> How long a cable do you want?
> 
> The pSeries (IBM rs6000) have remote IO drawers that attach via  ahigh speed 
> serial cable. The drawers house anything up to about 10 PCI slots. The cables 
> can get pretty long (i.e. in another rack, which means a few metres. I guess 
> the specs would be online somewhere on IBM's website. probably the cabling & 
> devices manual.
> 
> I think the trick is that you don't need to extend the PCI bus itself. You 
> actually need a PCI Bridge that happens to have it's two halves at a distance 
> from each other.
> 
> Now whether you can chain a PCI bridge off a PCI slot is another matter. I 
> don't know if you can. So I may just be flapping my jaw here... (IRQ's would 
> be a limitation wouldn't they?)

I suspect that these are 'channels' (IBM speak).  That is, there is 
probably a CPU and DMA controller at the far end of the cable.  In which 
case, there would be no direct communication with the PCI buses in the 
I/O drawer.  This could be serial SCSI but this would still need the CPU 
and DMA.

-- 
JRT