well the problem is pretty obvious.  mac68k/disksubr.c has:

#define NUM_PARTS 32

char *
readdisklabel(dev, strat, lp, osdep)
...
{
	...
	bp = geteblk((int)lp->d_secsize * (NUM_PARTS + 1));
	...
}


for a cdrom, lp->d_secsize is going to be 2k, so readdisklabel()
will try to allocate a buffer of size 2k * 33 = 66k, which is larger
than MAXBSIZE (which is 64k).

I'm guessing that readdisklabel() is really assuming that lp->d_secsize
is 512, in which case this would work out fine.  if the mac partition map
records are stored consectively on disk (rather than 1 entry per sector
as the code currently assumes) then we should be able to replace all of
the occuraces of "lp->d_secsize" with "512", and then round the argument
of geteblk() up to a multiple of lp->d_secsize.

could someone that has a cd with a mac partition table on it
check to see whether the partition map records are packed or
1 entry per sector?

-Chuck


On Wed, Oct 03, 2001 at 12:45:51PM -0400, Jim Mercer wrote:
> On Tue, Oct 02, 2001 at 09:20:58PM -0700, Chuck Silvers wrote:
> > what is the stack trace when it panics like this?
> > (type "t" in ddb)
> 
> sorry, i don't have a serial console, so this is by hand, if you need the
> specific numbers, i can get them by crashing it again.
> 
> panic: allocbuf: buffer larger than MAXBSIZE requested
> Stopped in pid 186 (cdparanoia) at _spu_Debugger+0x6:  unlk  a6
> db> t
> _cpu_Debugger(
> _panic(
> _allocbuf(
> _geteblk(
> _readdisk(
> _cdgetdisklabel(
> _cdopen(
> _spec_open(
> _VOP_OPEN(
> _vn_open(
> _sys_open(
> _syscall(
> _trap(
> 
> 
> > 
> > -Chuck
> > 
> > 
> > On Tue, Oct 02, 2001 at 03:15:15PM -0400, Jim Mercer wrote:
> > > 
> > > i've tried this with the current-20010915 SBC kernel and i have the
> > > current-20010915 userland.
> > > 
> > > i built and installed cdparanoia.
> > > 
> > > when i run it to query the drive, i get a panic/break to debugger:
> > > 
> > > panic: allocbuf: buffer larger than MAXBSIZE requested
> > > stopped in pid 16209 (cdparanoia) at _cpu_Debugger+0x6: unlk  a6
> > > 
> > > note: this same thing happened using binary package versions of other
> > > cdrom/audio tools on 1.5.0, 1.5.1 and 1.5.2.
> > > 
> > > hardware is:
> > > 
> > > Mac LC575, 36M, upgraded to full 68040
> > > 
> > > CD is Neil Young.  8^)
> > > 
> > > -- 
> > > [ Jim Mercer        jim@reptiles.org         +1 416 410-5633 ]
> > > [ Now with more and longer words for your reading enjoyment. ]
> 
> -- 
> [ Jim Mercer        jim@reptiles.org         +1 416 410-5633 ]
> [ Now with more and longer words for your reading enjoyment. ]