-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Hello,

On Jan 31, 2007, at 19:04, Allen Briggs wrote:

> On Wed, Jan 31, 2007 at 04:44:40PM -0500, Michael Lorenz wrote:
>> Yeah, I know what it's for - should probably be mentioned in spl(9)
>> since that man page claims that IPL_HIGH blocks all hard and soft
>> interrupts.
>
> Probably.  Maybe in a "CURIOSITIES" or "IMPLEMENTATION NOTES" section. 
>  :-)

Well, some other archs do the same, namely shark and prep, I'm pretty 
sure there are more, so it's not that much of a curiosity.

>> Hmm, pretty much all PowerMacs should support some sort of DMA at 
>> least
>> with the onboard serial ports anyway, and I've seen some unused code 
>> to
>> deal with that - any idea what's wrong with it?
>
> I don't.  I suspect that serial ports have mostly been used for 
> consoles
> where you don't want DMA, and the uses for modem/ppp/etc. have not
> overlapped with the development focus to get the DMA modes operational.
> But that's a lot of guesswork.

Stupid question - why wouldn't we want DMA at least for sending? Fill a 
buffer until the chip is idle, then feed it even if the buffer contains 
only a single byte. Same with reading, as long as we always know 
exactly what position in any given buffer is the last byte received ( 
or some sort of 'give me what you got so far' ). Of course that 
requires the chip to handle any sort of handshaking on its own.
I didn't mess with serial ports on Macs so far but I did my share of 
Z80 SIO programming some time before the previous ice age - if the mac 
serials aren't too retarded compared to the Z80 SIO they should support 
what we need here, including handshaking, parity, even some sort of 
CRC.

have fun
Michael
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.4 (Darwin)

iQEVAwUBRcFAacpnzkX8Yg2nAQKfnwf/TlYCjDpIa7I0cWyuv5M3sHPMdm+m/lbV
z7mFEbQ08nDf7KbBDh7p9U4Mp3UH7dcz2TQNDNYTaosisx8NB5EJ0MqRQ5Uqxhya
j2/tQLo/WWimn6iaUN3Cjsu1t0AYPCFQGKHPlw25OV9DHRN8fHG3c+TiZj8nromE
oaXgy+O0+rXf6RXT7UrxgMhpaxirXRnmOPse/CurvxTRiaZUp3ZTDkWzAgdLpQno
2TrA6LVMG5dE0xcuD6UpZeGf94WAMRO6mZiM0FKY1RcanwTmMYx8C+SBo0oUUlLP
BZlLt6Lx/laDsWGHc3ZZoAR8U7dadcyKWrcLx0txFNY6S9zWj/Mm/w==
=TUGo
-----END PGP SIGNATURE-----