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Date:      Fri, 04 Jul 2008 15:06:48 -0700
From:      Marcel Moolenaar <xcllnt@mac.com>
To:        John Baldwin <jhb@freebsd.org>
Cc:        Alexey Shuvaev <shuvaev@physik.uni-wuerzburg.de>, freebsd-current@freebsd.org, Dmitry Morozovsky <marck@rinet.ru>
Subject:   Re: puc(4) man page update?
Message-ID:  <70771DF0-71BB-453F-949E-6A50DD7D0D71@mac.com>
In-Reply-To: <200807041733.25301.jhb@freebsd.org>
References:  <20080701181358.GA93601@wep4017.physik.uni-wuerzburg.de> <20080704135827.H35668@woozle.rinet.ru> <22A6B038-44BB-4072-8A6E-8C1D5855CB14@mac.com> <200807041733.25301.jhb@freebsd.org>

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On Jul 4, 2008, at 2:33 PM, John Baldwin wrote:

> On Friday 04 July 2008 03:31:41 pm Marcel Moolenaar wrote:
>>
>> On Jul 4, 2008, at 2:59 AM, Dmitry Morozovsky wrote:
>>
>>> doesn't splitting uart out of kernel broke serial console? Last time
>>> I checked
>>> it did.
>>
>> Yes, it does. The serial console is setup/initialized and
>> used before pre-loaded modules are linked and/or usable.
>> We don't have the support in place that allows you to boot
>> without console until pre-loaded modules are initialized,
>> at which time add a low-level console device is setup.
>> It's not that hard to do, I think.
>>
>> So, currently low-level console drivers, such as dcons(4),
>> sio(4) and uart(4) need to be compiled into the kernel.
>> Consequently any devices/busses to which any of these can
>> attach must be compiled into the kernel as well. Of these
>> acpi(4) and puc(4) are good examples. acpi(4) is a good
>> example because we use hints to work around the issue and
>> have sio(4) attach to isa(4) instead...
>
> Actually, sio does attach to acpi0.  What happens for sio is that the
> low-level console stuff is just doing bare-bones inb/outb anyway.   
> sioX
> devices do attach to acpi0 though just fine.

That's because sio(4) compiles-in the acpi bus attachment
even if acpi is not compiled-in. That's cheating :-)

-- 
Marcel Moolenaar
xcllnt@mac.com






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