hall@usfvax2.UUCP (12/10/86)
We have encountered the following system problem and wonder if any one
out there knows about it. We are running 4.2bsd on a VAX 11/750.
With a program in Modula-2 compiled, with the
Modula-2 compiler from DEC's western research lab, using the -g option
for the dbx debugger we get a bad runtime problem. When we get in dbx
and read in the symbolic information and executable code and then type
run the operating system crashes with the message "panic:munhash".
This does not occur when we try to run the program outside of dbx. Does
anyone know what the error panic:munhash means? A way to fix it? A
way around it? Something in a Modula-2 program that might cause it? If
anyone has any answers, please send them to me be electronic mail.
Thanks.
--
Larry Hall
Usenet: {seismo,gatech,crash}!akgua!usfvax2!hall
CS-Net: hall@usf.CSNETmouse@mcgill-vision.UUCP (der Mouse) (12/13/86)
In article <424@usfvax2.UUCP>, hall@usfvax2.UUCP (Dr. Larry Hall) writes: > We have encountered the following system problem and wonder if any > one out there knows about it. We are running 4.2bsd on a VAX 11/750. > When we get in dbx and read in the symbolic information and > executable code and then type run the operating system crashes with > the message "panic:munhash". > This does not occur when we try to run the program outside of dbx. > Does anyone know what the error panic:munhash means? Our 4.2 system would crash reliably with panic: munhash whenever anyone attempted to set a breakpoint with any debugger. Poking around, it turned out that it crashed whenever anyone attempted to use ptrace() to write to the child's text segment (which setting a breakpoint does). There were two casts in the kernel which, though perfectly correct, produced incorrect code because there was something wrong with the compiler. You could comment out the casts in the source, or even just adb the kernel and change two instructions (extv to extzv, I think). I forget further details, but someone posted the fix to net.unix-wizards at the time (this was some time ago, it was still called net.unix-wizards). If nobody comes forward with this, I can go to the backup tapes and resurrect our 4.2 kernel source long enough to dig out these changes (we aren't running 4.2 any more). der Mouse USA: {ihnp4,decvax,akgua,utzoo,etc}!utcsri!mcgill-vision!mouse think!mosart!mcgill-vision!mouse Europe: mcvax!decvax!utcsri!mcgill-vision!mouse ARPAnet: think!mosart!mcgill-vision!mouse@harvard.harvard.edu [USA NSA food: terrorist, cryptography, DES, drugs, CIA, secret, decode]