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Date:      Fri, 04 Jul 2008 12:42:35 -0700
From:      Marcel Moolenaar <xcllnt@mac.com>
To:        "M. Warner Losh" <imp@bsdimp.com>
Cc:        arch@freebsd.org, sam@freebsd.org, freebsd-current@freebsd.org, ed@80386.nl
Subject:   Re: MPSAFE TTY schedule [uart vs sio]
Message-ID:  <C7053D65-A0F0-4ACD-A68D-49A4AD6805AE@mac.com>
In-Reply-To: <20080704.063540.1210476607.imp@bsdimp.com>
References:  <20080703205220.GW14567@hoeg.nl> <486D4006.2050303@freebsd.org> <993E865A-A426-4036-9E09-A87D7474DE80@mac.com> <20080704.063540.1210476607.imp@bsdimp.com>

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On Jul 4, 2008, at 5:35 AM, M. Warner Losh wrote:

> : I looked into it in 2003 but since I don't have any hardware,
> : I wasn't the one able to do it. I think the fundamental problem
> : is that the BRG is not part of the UART itself and needs a
> : separate handle or even (tag, handle) pair to access. That's as
> : far as I know the only big thing about the work.
> :
> : For me not having access to the hardware is a showstopper for
> : looking into it myself.
>
> Do you need physical access?

No, not at all. As long as the USART is connected to another
UART that I can access and as long as I can load/unload the
uart(4) module, I should be able to write the support for
it.

Even only restricted sudo(1) should be fine.

>  I have a pc98 machine I can put back on
> the network.  It has the 8251 chip in it.  It also has a 16550 part as
> well since it is a later model which had both...

Perfect. A null-modem cable between the two of them and I
should be all set.

-- 
Marcel Moolenaar
xcllnt@mac.com






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