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Date: Thu, 09 Feb 2006 18:36:10 +0100
From: Matthias Andree <matthias.andree@gmx.de>
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To: Joerg Schilling <schilling@fokus.fraunhofer.de>
CC: jengelh@linux01.gwdg.de, peter.read@gmail.com,
       linux-kernel@vger.kernel.org, jim@why.dont.jablowme.net
Subject: Re: CD writing in future Linux (stirring up a hornets' nest)
References: <200602031724.55729.luke@dashjr.org> <43E7545E.nail7GN11WAQ9@burner> <73d8d0290602060706o75f04c1cx@mail.gmail.com> <43E7680E.2000506@gmx.de> <20060206205437.GA12270@voodoo> <43E89B56.nailA792EWNLG@burner> <20060207183712.GC5341@voodoo> <43E9F1CD.nail2BR11FL52@burner> <20060208162828.GA17534@voodoo> <43EA1D26.nail40E11SL53@burner> <20060208165330.GB17534@voodoo> <43EB0DEB.nail52A1LVGUO@burner> <Pine.LNX.4.61.0602091729560.30108@yvahk01.tjqt.qr> <43EB7210.nailIDH2JUBZE@burner> <Pine.LNX.4.61.0602091813260.30108@yvahk01.tjqt.qr> <43EB7BBA.nailIFG412CGY@burner>
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Joerg Schilling wrote:
> Jan Engelhardt <jengelh@linux01.gwdg.de> wrote:
> 
>>>>> Please explain me:
>>>>>
>>>>> -	how to use /dev/hd* in order to scan an image from a scanner
>>>>> -	how to use /dev/hd* in order to talk to a CPU device
>>>>> -	how to use /dev/hd* in order to talk to a tape device
>>>>> -	how to use /dev/hd* in order to talk to a printer
>>>>> -	how to use /dev/hd* in order to talk to a jukebox
>>>>> -	how to use /dev/hd* in order to talk to a graphical device
>>>>>
>>>> With /dev/sg, this was possible?
>>> Of course!
>>>
>> But you need to open the correct /dev/sg[0-9] too, don't you?
>> (otherwise cdrecord would set the jukebox on fire)
> 
> This is why the mapping engine is in the Linux adoption part of
> libscg. It maps the non-stable device <-> /dev/sg* relation to a
> stable b,t,l address.

Well, the b,t,l mapping, judging from libscg code, is as stable as the
ordering of the device nodes themselves, so it is not clear what the
advantage would be other than getting a uniform and artificial b,t,l mapping.

If hotplugging shuffles /dev/sg* between running $APPLICATION -scanbus and
$APPLICATION -dowhatever, the b,t,l will change as well.