From mboxrd@z Thu Jan  1 00:00:00 1970
From: will.senn@gmail.com (Will Senn)
Date: Wed, 9 Dec 2015 11:55:06 -0600
Subject: [TUHS] v6tar from v7 on v6, too large?
In-Reply-To: <20151209045357.8573718C0C5@mercury.lcs.mit.edu>
References: <20151209045357.8573718C0C5@mercury.lcs.mit.edu>
Message-ID: <56686AFA.1080205@gmail.com>



On 12/8/15 10:53 PM, Noel Chiappa wrote:
>      > From: Will Senn <will.senn at gmail.com>
>
>      > The problem is this, when I attempt to execute the v6tar binary on the
>      > v6 system (it works in v7) it errors out:
>      > v6tar
>      > v6tar: too large
>
> That's an error message from the shell; the exec() call on the command
> ('v6tar') is returning an ENOMEM error. Looking in the kernel, that comes from
> estabur() in main.c; there are a number of potential causes, but the most
> likely is that 'v6tar' is linked to be split I+D, and your V6 emulation is on
> a machine that doesn't have split I+D (e.g. an 11/40). If that's not it,
> please dump the a.out header of 'v6tar', so we can work out what's causing the
> ENOMEM.
>
> 	Noel
Noel,

I followed the thread you provided and I appreciate the direction. 
estabur(who thought these names up, I know 8 characters is limiting, but 
c'mon) is indeed the culprit:
         if(sep) {
                 if(cputype == 40)
                         goto err;

I'm gathering (read still investigating) that the 411 header is read by 
a loader and the call to estabur is made with a value for sep indicating 
that it is a split I+D binary, then the cputype is checked and sure 
enough, it's a PDP-11/40 and the error is generated.

Thanks,

Will