Re: PATCH: cdrecord: avoiding scsi device numbering for ide devices

[Thomas Zimmerman <thomas@zimres.net>]

On 09-Aug 10:51, Albert Cahalan wrote:
> On Tue, 2004-08-10 at 00:47, Con Kolivas wrote:
> > Albert Cahalan writes:
> > > On Mon, 2004-08-09 at 18:59, Con Kolivas wrote:
> > >> Albert Cahalan writes:
> 
> > >> > Joerg:
> > >> >    "WARNING: Cannot do mlockall(2).\n"
> > >> >    "WARNING: This causes a high risk for buffer underruns.\n"
> > >> > Fixed:
> > >> >    "Warning: You don't have permission to lock memory.\n"
> > >> >    "         If the computer is not idle, the CD may be ruined.\n"
> > >> > 
> > >> > Joerg:
> > >> >    "WARNING: Cannot set priority class parameters priocntl(PC_SETPARMS)\n"
> > >> >    "WARNING: This causes a high risk for buffer underruns.\n"
> > >> > Fixed:
> > >> >    "Warning: You don't have permission to hog the CPU.\n"
> > >> >    "         If the computer is not idle, the CD may be ruined.\n"
> > >> 
> > >> Huh? That can't be right. Every cd burner this side of the 21st century has 
> > >> buffer underrun protection.
> > > 
> > > I'm pretty sure my FireWire CD-RW/CD-R is from
> > > another century. Not that it's unusual in 2004.
> > > 
> > >> I've burnt cds _while_ capturing and encoding 
> > >> video using truckloads of cpu and I/O without superuser privileges, had all 
> > >> the cdrecord warnings and didn't have a buffer underrun.
> > > 
> > > That's cool. My hardware won't come close to that.
> > > Burning a coaster costs money.
> > > 
> > > Let me put it this way: $$ $ $$$ $$ $ $$$ $$ $
> > > 
> > > The warning, if re-worded, will save people from
> > > frustration and wasted money.
> > 
> > Sounds good; how about something less terrifying? That warning sounds like a 
> > ruined cd is likely.
> 
> I'm not about to burn CDs trying, but I do believe
> that "a ruined cd is likely" would be accurate if I
> were to keep busy with Mozilla and such. OpenOffice
> would surely ruin a cd. Light web browsing makes my
> mp3 player skip.
> 
> Not all of us have hardware like you do. Encoding
> video is something I wouldn't bother to try, even
> without the CD burner going!
> 
> (the box isn't that old; it's fanless though)
> 

I've only created coaster _with_ the suid bit while ab^H^Husing the 
computer to do other things--like compiling a new kernel. 2.6 is much
better at setting up DMA access to the drive; 2.4 would use huge amounts
of system time (> 90%). When that happened, the system felt like it was 
out to lunch--mouse cursor updates would sometimes take >2 seconds. 
Cdrecord used more cpu if it was suid. I haven't had a problem in 2.6.
The  warning is counter to my expericnce with cdrecord. I think the
warning would be worded better as:

"Warning: Cdrecord was unable to get exclusive access to the cpu."
"Warning: This may cause Buffer underruns from other activity."

and

"Warning: Cdrecord was unable to get exclusive access to memory."
"Warning: This may cause Buffer underruns from other activity."

But drop the first one if you're on >2.6.

Thomas