On the transfer of data from the uart.c driver to the tty layer...

Benjamin Herrenschmidt benh at kernel.crashing.org
Wed Sep 6 10:45:26 EST 2006

On Tue, 2006-09-05 at 14:56 +0000, Alejandro C wrote:
> Hi all,
> I'm working on a the uart.c driver to add support for SCCs in HDLC mode. The 
> application I'm going to run on top will be sending Ethernet packets 
> encapsulated in the data field of an HDLC frame. The idea was to make the 
> buffer big enough so that a whole Eth. packet (max 1518 octects) could fit 
> in just one buffer. I let the CPM interrupt on a frame basis and the problem 
> I've come across is that the receive buffer in the struct tty_struct, where 
> the tty layer collects the data from the driver 
> (tty_struct.tty_flip_buffer.char_buf), is only 1024 bytes 
> (2*TTY_FLIPBUF_SIZE). The easiest at this stage would be to make those 
> buffers larger, but I don't know what sort of impact this might have... Any 
> tips?
> Any ideas on how to solve it in another fashion?
> Help will be highly appreciated.

You should ask on the linux-kernel mailing list, possibly CC'ing Alan
Cox who seem to have put his hands a lot in the TTY code lately.


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