Re: cd burning: kernel / userspace?

[Alan Jenkins <sourcejedi@phonecoop.coop>]

Wakko Warner wrote:

>Please keep me CC
>
>  
>
>>A script would be cool, but dd doesn't do the memory locking and real 
>>time priority stuff.  I don't know how important this is - how old your 
>>hardware would have to be for you to get "coasters" (buffer underun) 
>>without it.
>>    
>>
>
>Agreed, however, I was attempting to make a point by saying dd.
>
>  
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>>Theres an option in cdrecord to fixate an arbitrary disk (one without a 
>>TOC for whatever reason), and one not to fixate the disk you're writing, 
>>so it looks like fixation could and should be done on demand using an 
>>ioctl.  You'd also need ioctls to deal with multiple sessions.
>>    
>>
>
>Already thought of this.  But how to deal with it, I don't know.
>
>  
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>>I think most people would want a cdrwtool that basically pretends to be 
>>cdrecord (in some ways ;), because thats the most intuitive way to do it 
>>- even if you can do everything you want to with cdrwtool for the ioctls 
>>and dd for the data.
>>    
>>
>
>That did come to mind, as long as I don't have to use dev=x,y,z (joerg you
>listening?  Another user steps up to say he hates it =)    heheh.
>
>  
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>>I've definitely underestimated the problems with my idea, and I can't 
>>see any tangible benefits which couldn't be obtained by hacking
>>    
>>
>
>I can, like someone else specified.  Unlike windows, linux users can put
>whatever filesystem (or just plain data) on a cd they choose.
>
>They wanted to specify their cdrw to send stuff directly to it and change
>cds.  Something like this (so long as the driver supports it too):
>
>cdrwtool /dev/scd0 -ejectonclose -fixateonclose
>	note could possibly do -dao with a fixed size.
>	also, I don't know dump's options so I'm improvising
>dump -D /dev/scd0 -B 700MB /home
>
>When dump fills 700mb, it will close and await the user.  Since the driver
>was told to fixate and eject on close, the cd comes out ready.  I understand
>buffer underruns here and for starters, underruns aren't part of this
>picture, it can come later (ie after proof of concept)
> 
>  
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>>cdrecord.  Idealistically, its the right thing to do - but in practice 
>>its unessecary, I'm not up to the job, and its not attractive enough for 
>>someone to pick up.  After packet writing is seamlessly merged into the 
>>uniform cdrom driver it might start looking more important, and I might 
>>have learnt enough to at least implement a proof of concept.  I'm still 
>>interested in hashing out more details and potential benefits.
>>    
>>
>
>Frankly, I have found that growisofs is awkward to use.  I could hack it to
>be better suited for what I wanted to do (I can't pipe data into it.  I used
>to do mkisofs on one machine, send the data over the network and burn at the
>same time.)  However, it's not as bad as dev=x,y,z
>
>For me, if this were implemented in kernel, I could do this:
>nail:~> mkisofs -r -no-pad /80g/debian/x/vol200 | \
>	ssh vegeta 'cat > /dev/scd0'
>
>(nail is a disk server, vegeta is the box with the burner on /dev/scd0,
>that's my current setup)
>
>  
>
Sorry, I'm not very good at this list / person CC stuff.  I sent a reply 
to Valdis.Kletnieks@vt.edu, but forgot to CC to list.  Contents as follows:

I'm not sure this is necessary.  Can't you just do:

# dump -0 -B 700000 -u -z3 /home -f -| cdrecord /dev/hdb -

dump and cdrecord allow you to use "-" as a filename to indicate that 
output shoud be written to stdout and input should be read from stdin 
respectively.