You should look at any of PCI bus-master Ethernet cards,
which have exactly the same problemset.
...
> 1.) I will use up "expensive" below-16MB-memory which ought to be
> kept for ISA-DMA applications.
Perhaps you want 'GFP_DMA32' allocations ?
And if the buffer isn't in appropriate area, non-irq-space
part of your driver must copy things over into appropriate
area for transmit.
Such allocation space does not exist, though...
Do you *really* have more than 1 or 2 GB RAM at your box ?
> 2.) When asked by the network subsystem to transmit a buffer I can
> not choose the kind of memory the data is provided in. I can only
> either copy it around or take the risk it will be pulled away
> under my feet.
No, data waiting for transmit won't be pulled away before
your driver gives a permission for it. You are implying
of giving that permission too early..
> Comments?
> -- Jens
/Matti Aarnio <matti.aarnio@sonera.fi> oh2mqk
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