Date: Thu, 13 Nov 1997 13:48:31 -0800 (PST) From: Simon Shapiro <Shimon@i-connect.net> To: (John Kelly) <mouth@ibm.net> Cc: hackers@FreeBSD.ORG, Bruce Evans <bde@zeta.org.au> Subject: Re: Status of 650 UART support Message-ID: <XFMail.971113134831.Shimon@i-Connect.Net> In-Reply-To: <346d4ceb.8671504@smtp-gw01.ny.us.ibm.net>
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Hi John Kelly; On 13-Nov-97 you wrote: > On Thu, 13 Nov 1997 20:35:53 +1100, Bruce Evans <bde@zeta.org.au> > wrote: > > >>Why can't we handle large bursts of input? > > > >Buffer sizes are finite. > > Can't we use malloc to create elastic buffers on the fly? Is that a > no-no in the kernel? > > >Multiply some of these numbers by 4 for 64-bit fifos and you have > >seriously high (normal worst case) latencies. (My definition of > >``high'' > >is anything that would stop an 8250 from working at 115200 bps - 87 > >usec :-). I will reduce this when faster speeds become common.) > > Why not start from scratch and develop siov2.c which uses elastic > buffers, 650 polled vs. interrupt mode switching, yada, yada, yada. > Sio.c could still be the default while siov2.c could be selected on a > port by port basis with a kernel config flag. > > Now if someone foolhardy enough to undertake such a project would step > forward (don't look in my direction, I know better). ;-) a. Define ALL the entry points into the driver b. Gather the documentation for all UARTs you want to work b. Send to Simon If the answer to a. or b. is ``read the code'' then do not do c. :-) --- If Microsoft Built Cars: Every time they repainted the lines on the road, you'd have to buy a new car. Sincerely Yours, Simon Shapiro Atlas Telecom Senior Architect 14355 SW Allen Blvd., Suite 130 Beaverton OR 97005 Shimon@i-Connect.Net Voice: 503.799.2313
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