From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fabrice Gautier To: 'Andrew Lunn' Cc: eCos Disuss Subject: RE: [ECOS] Re: Port of 82559 ethernet driver for PC target (was: "RE: [ECOS] New bie Question!") Date: Wed, 04 Oct 2000 11:55:00 -0000 Message-id: <8AE4B526B977D411841F00A0CC334020052C82@cuz-exchange.sdesigns.net> X-SW-Source: 2000-10/msg00029.html 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