From: Sean Dwyer via TUHS <tuhs@minnie.tuhs.org>
To: Warner Losh <imp@bsdimp.com>
Cc: TUHS main list <tuhs@minnie.tuhs.org>
Subject: Re: [TUHS] wump.c for v6
Date: Tue, 7 Jan 2020 15:04:47 -0500 [thread overview]
Message-ID: <20200107200447.GA3211@mail.ewe2.ninja> (raw)
In-Reply-To: <CANCZdfoEhGBzy13mGvw8jJNz0pvYVjBFy3-9BQ0mN8-4HB7bLw@mail.gmail.com>
On Mon, Jan 06, 2020 at 11:48:02AM -0700, Warner Losh wrote:
> On Mon, Jan 6, 2020 at 11:38 AM Will Senn <will.senn@gmail.com> wrote:
>
> > On 1/6/20 12:29 PM, Warner Losh wrote:
> >
> > The good news is that disassembly will tell you right away if it was
> > written in C or not.
> >
> >
> > OK. I give up. How?
> >
>
> Generally, the C compiler generates code that's quite distinctive (at least
> PCC does, not sure about Dennis' compiler). People writing free assembler
> tend to do really weird things for function entry / return.
>
> And it will likely tell you if it's some weird wrapper around another
> binary, though that wasn't too common at bell labs.
>
> Warner
A while back I did some analysis (https://ewe2.ninja/computers/cno/) of
another source-less v6 binary, cno. Fortunately, it hadn't been stripped but I
still did some disasembly because of the interesting differences. v6 binaries
have a different crt0 preamble and simpler subroutine setup, and I narrowed
dowh the library code to an intermediate stage of iolib (which IIRC still
exists in the UNSW archive on TUHS). There's a few cribs in that essay to help
you figure out some basic things, pdp11 assembly isn't hard to decode.
--
I love deadlines. I love the whooshing noise as they fly by.
next prev parent reply other threads:[~2020-01-07 20:14 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-06 6:13 Will Senn
2020-01-06 15:20 ` Clem Cole
2020-01-06 15:24 ` Clem Cole
2020-01-06 16:25 ` Will Senn
2020-01-06 16:35 ` Clem Cole
2020-01-06 18:29 ` Warner Losh
2020-01-06 18:38 ` Will Senn
2020-01-06 18:48 ` Warner Losh
2020-01-06 21:08 ` Clem Cole
2020-01-06 21:38 ` Clem Cole
2020-01-06 22:14 ` Warner Losh
2020-01-06 23:46 ` Will Senn
2020-01-07 20:04 ` Sean Dwyer via TUHS [this message]
2020-01-07 21:08 ` Clem Cole
2020-01-08 6:35 ` Sean Dwyer via TUHS
2020-01-06 19:10 ` Bakul Shah
2020-01-06 20:29 ` Will Senn
2020-01-07 0:40 Noel Chiappa
2020-01-07 0:44 ` Warner Losh
2020-01-07 1:58 Noel Chiappa
2020-01-10 14:27 Noel Chiappa
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