[TUHS] Deleted lib1 and lib2 in v6, recoverable?
Will Senn
will.senn at gmail.com
Sat Dec 29 11:26:23 AEST 2018
Ah! Thanks Noel. Yes, the two files are created and then a slew of linker errors. What you say makes sense. I can just compare with another v6 instance that I have that is similar to replicate the delivered order. Now I’m off to trying it out.
Will
Sent from my iPhone
On Dec 28, 2018, at 7:09 PM, Noel Chiappa <jnc at mercury.lcs.mit.edu> wrote:
>> From: Will Senn
>
>> I whacked /usr/sys/lib1 and lib2 'accidentally' meaning I logged in as
>> bin changed to /usr/sys and typed rm lib1 and rm lib2 :).
>
> Doesn't sound very accidental... :-)
>
>> sh run as bin doesn't do it.
>
> Odd. 'run' in /usr/sys on my V6 machine (not that I use that, mind) says:
>
> chdir ken
> cc -c -O *.c
> ar r ../lib1
> rm *.o
> chdir ../dmr
> cc -c -O *.c
> ar r ../lib2
> rm *.o
>
> which should regenerate them - sort of. I suspect you really meant 'doing sh
> run creates a lib1 and lib2, but then I get errors from the ld phase with
> missing symbols'. Yes?
>
> If so, the thing is that the V6 linker won't pull in an object module from a
> library unless a global in it satisfies an already existing (i.e. in the
> linking process) undefined global. (I don't know if this is true of later
> linkers; never used 'em.) In other words, when loading a multi-module system,
> the module with 'main' has to be first, and then the rest in an order such
> that each one holds a previously-undefined symbol.
>
> So the order of the object modules you'll get in lib? from the above, if you
> precede them with 'rm lib?', is probably not the right order. (The above shell
> script assumes they already exist, with the modules in the right order, so the
> above just replaces them with the newly compiled versions...)
>
>> So, what magic incantation is required to rebuild them.
>
> Here's the ordering in lib1:
>
> main.o
> alloc.o
> iget.o
> prf.o
> rdwri.o
> slp.o
> subr.o
> text.o
> trap.o
> sig.o
> sysent.o
> clock.o
> fio.o
> malloc.o
> nami.o
> pipe.o
> sys1.o
> sys2.o
> sys3.o
> sys4.o
>
> Other orders would work too (e.g. you could move sys?.o up just after sysent.o
> and it should work).
>
> My lib2 is somewhat odd, so I hesitate to list it, but since most modules in
> dmr are pulled in from entries in c.c, almost any order will work, I think.
>
> Noel
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