[ECOS] Re: Port of 82559 ethernet driver for PC target (was: "RE: [ECOS] New bie Question!")

[Fabrice Gautier]

Hi,

> -----Original Message-----
> From: Andrew Lunn [ mailto:andrew.lunn@ascom.ch ]
> Sent: Wednesday, October 04, 2000 12:34 AM
> To: Fabrice Gautier
> Cc: eCos Disuss
> Subject: [ECOS] Re: Port of 82559 ethernet driver for PC target (was:
> "RE: [ECOS] New bie Question!")
> 
> 
> Well, on the EBSA you have to tell the MMU not to use the read cache
> or the write buffer for the memory in the PCI window. I presume the
> same applies for the 386-PC?

The good news is  that the i386 port of eCos doesn't seem to have the cache
enabled.
 
> It has to be in the PCI window and somewhere the DMA can get it. I
> know in olden days the i386 hardware was limmited on where the DMA
> could work. Does this apply? Its a long time since i've played with
> this sort of thing.

The DMA? I'm not sure but I don't see any programming of a DMA controller in
the existing driver.
Unless there is part of the RAM that is not "connected" to the PCI bus I
guess all of it is accessible, but why would it be so? Does the DMA thing is
what connect the PCI bus to the RAM ?

Anyway I think the DMA limitation is something like we can't do DMA
transfert to/from memory above 16 Meg - And I don't have more than 16 Meg on
my target.

And Anyway, I will assume there is nothing to worry about... and we will
see.

Regards,

-- 
Fabrice Gautier
fabrice_gautier@sdesigns.com