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 Post subject: NE2000 true remote dma and io mode?
PostPosted: Thu Feb 27, 2020 11:44 am 
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Joined: Mon Mar 12, 2018 12:31 pm
Posts: 2
well i'm getting a bit insane reading about NE2000.
i've got an ISA8-16 bit card with an UM9003F chip (NIC/SNI), that doesn't have any kind of DMA lines.

According to documents so far i see, (DP8390D/NS32490D NIC Network Interface Controller):
a remote dma would use the "remote dma port" to make block transfers using the host DMA controller preconfigured with an address page (between host memory and local memory, if send, adjusting the BNDY pointer at rx ring buffer after remove the packet), and that theres the a mention "just a mention" that you can do it manually by writing/reading to that port.
(however the port isn't mentioned in the registers)

According to RTL8019AS, that remote port is located at registers 0x10:1F, and almost everywhere i found a piece of code doing I/O after placing the Command to do remote DMA (incluing OSdev page).

I'm a little puzzeled where: how can you identify a card by software that is going to use a true DMA channel; does NE2000 specs have some way to know if the card supports remote DMA (tru the DMA controller)? If the card uses DMA tru the controller theres a way to configure it to use just IO.


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