William Corcoran wlc at jctaylor.com
Fri Dec 22 08:12:33 AEST 2017

Hello Team TUHS: 

I am having a problem with my PDP-11 SVR1 running under a recent SIMH build.  My problem occurs on both MAC OS X and FreeBSD.  

First, I created a six disk (RP06) and eight port TTY (DZ) kernel, with swap placed on drive 1.  The system behaves beautifully as FSCK reports clean.  Eight users can login with no problem.  

Second, I reverted to a pristine PDP-11 SVR1 with one drive (RP06) and no DZ and booted the default kernel (gdtm) and I see the same problem described below.

Third, when using the tape driver instead of /dev/null i get the same results.   

Next, here is the issue: 

cd / 
find . -print | cpio -ocvB > /dev/null 

It runs for a short while and then shitz a core: 
I am using /dev/null to take the tape driver out of the equation.  

Here is the backtrace for cpio:  


Now, interestingly,  I run into a similar issue when using tar: 

cd  /usr
tar -cvf /dev/null . 

Again, this will run for a while, then drops a core.  Here is the backtrace for tar:  


This really bugging me since my SVR1 is otherwise working flawlessly.  I was able to remake the entire system and custom kernels that boot with no problem.   
Also, I configured my main port to run inside the AWS Lightsail and now I have access to SVR1 from anywhere in the world!

I was also wondering if doing a CPIO or TAR on the entire system was overflowing some link tables and maybe this is expected behavior for the minimal resource of the PDP-11?

Thank you for any help.   

Would you expect tar or cpio to dump core if you attempted to copy large filesystems  (or the entire system) on a PDP-11? 
Note: All of my testing has been in single user mode.   


Bill Corcoran  

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