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RE: Re: Port of 82559 ethernet driver for PC target (was: "RE: New bie Question!")
- To: 'Andrew Lunn' <andrew dot lunn at ascom dot ch>
- Subject: RE: [ECOS] Re: Port of 82559 ethernet driver for PC target (was: "RE: [ECOS] New bie Question!")
- From: Fabrice Gautier <Fabrice_Gautier at sdesigns dot com>
- Date: Wed, 4 Oct 2000 11:52:36 -0700
- Cc: eCos Disuss <ecos-discuss at sourceware dot cygnus dot com>
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