Re: Network inteface w/ DMA

Jan Kasprzak (kas@informatics.muni.cz)
Fri, 04 Sep 1998 21:19:43 +0200


Alan Cox wrote:
: > can send/receive packets via ISA DMA. Is there any way of telling kernel
: > to pass a DMA-able memory only to the dev->hard_start_xmit()
:
: No you need to use bounce buffers. Theres an example in the z85230 driver
: on ftp.linux.org.uk:pub/linux/alan - thats a sync card using bounce
: buffers when needed
:
Thanks, I have already looked at drivers/net/ni65.c which
apparently uses bounce buffers too.

As for your Z85230-alpha-1.gz driver: It seems I have finaly
found a general-enough Sync PPP and Cisco HDLC layer implementation
for Linux. Is the interface (sppp_attach/detach etc) stable enough that I
can use it in my driver? And how can I switch between the PPP/HDLC modes?

: > (The rx side is easy because the skb is allocated in the device's
: > own interrupt routine and I can use alloc_skb(..., ...|GFP_DMA) here).
:
: Be aware that all the atomic memory pools may not contain any ISA DMA memory
: and that may be a stable state. ie dont do it , or if you do have
: a bounce buffer fallback

OK, I will implement the fallback to a pre-allocated bounce-buffer.

-Yenya

--
\ Jan "Yenya" Kasprzak <kas at fi.muni.cz>       http://www.fi.muni.cz/~kas/
\\ PGP: finger kas at aisa.fi.muni.cz   0D99A7FB206605D7 8B35FCDE05B18A5E //
\\\             Czech Linux Homepage:  http://www.linux.cz/              ///
If there are race conditions in programs fix them. The "my programs suck fix
something else" mentality leads you to things like Java.         -- Alan Cox

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