Re: Request for cooperation with all burn backends
On 10/10/06, Andy Polyakov <appro@fy.chalmers.se> wrote:
As for locking, or rather serializing access to [relevant] devices.
"Very portable" customarily means support for different operating
systems. But the trouble is that the other systems, other than Linux
that is, might and already do have own ways to serialize the access. It
might be impossible and/or simply inappropriate not to use these
mechanisms. Doesn't this kind of doom all "very portable" attempts as
simply unachievable?
"Very portable" almost alwas == "equally crippled on all platforms".
I'm so tired of 'very portable' software.
Secondly. Why do you address back-end developers? Is it really a problem
between recording programs? Isn't auto-mounting/-playing facilities
interfering with ongoing recording *bigger* problem?
[...]
Have you seen resmgrd? Well, it didn't seem to catch up, but anyway...
Why didn't it catch up? If you want my opinion, I think that all
attempts to achieve the goal *purely* in user-land are doomed. 2.6
O_EXCL on block device appears to be sufficient for intended purpose and
I personally would rather prefer it back-ported to 2.4 than some
user-land facility.
I had it explained to me in great detail how it was perfectly correct
to cripple the RedHat version of CDParanoia such that only one could
ever be running at a time-- because its autoscanning would always
block on advisory locks if any other program was using any other
CDROM/DVDROM device on the machine. Why? Because it was somehow
easier than fixing Nautilus's automount/autoplay tendencies to turn
every burn into a coaster.
I like the idea of having a convention-- but I would argue against it
locking down devices against all access. A CDROM device is perfectly
capable of answering, eg, ' are you a cdrom?' whil e burning. I
realize that deciding what access is 'safe' is underspecified right
now.
Note that it doesn't have to be /dev/sg.
/dev/sg is dead. Long live SG_IO.
To summarize. My vote goes for block device addressing, back-porting of
O_EXCL to 2.4 and convincing auto-mounting/-playing developers to stick
to it.
I will not be obeying O_EXCL in cdparanoia, at least in its current
form. However, I also want to make cdparanoia safe in the context of
cdrom devices ripping.
Monty
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