[Simh] SIMH dies when using ftp or wget

[Jan-Benedict Glaw]

On Mon, 2011-09-19 18:33:37 +0200, Arpadffy Zoltan <Zoltan.Arpadffy at scientificgames.se> wrote:
> Yes, it is possible to reproduce.
> It dies that not just the host exists, but the simh process also creases.
> 
> Here is the case:
[...]
> [root at mailhost ~]# ftp ultrix
> Connected to ultrix (192.168.10.4).
> 220 ultrix FTP server (ULTRIX Version 4.1 Sun Sep 17 06:28:20 EDT 1995) ready.
> Name (ultrix:ubul): zoli
> 331 Password required for zoli.
> Password:
> 230 User zoli logged in.
> ftp> bin
> 200 Type set to I.
> ftp> put starter.tar.gz
> local: starter.tar.gz remote: starter.tar.gz
> 227 Entering Passive Mode (192,168,10,4,4,1)
> 150 Openning data connection for starter.tar.gz (192.168.10.36,54533).
> 
> It works well until I issue the put command - but then the simh process gets a segmentation fault.
> 
[...]
> read(0, "", 1)                          = 0
> poll([{fd=9, events=POLLIN}], 1, 0)     = 0 (Timeout)
> read(0, "", 1)                          = 0
> poll([{fd=9, events=POLLIN}], 1, 0)     = 0 (Timeout)
> read(0, "", 1)                          = 0
> poll([{fd=9, events=POLLIN}], 1, 0)     = 0 (Timeout)
> read(0, "", 1)                          = 0
> --- SIGSEGV (Segmentation fault) @ 0 (0) ---
> 
> The same happens if I try to ftp get put or just use wget with
> bigger files from the simh client.

A SIGSEGV means that this is a bug inside SIMH. The next step would be
to recompile the SIMH VAX binary (and all needed object files) without
any -O flag (switch off optimizations) and with the -g flag (to
include debug information into the resulting files).

Done with that, start SIMH again and attach gdb to it
(gdb <pid-of-simh>). You'll be given a prompt, just "cont"inue.

Then start your FTP/wget/whatever session and wait until it crashes.
Once that happened, you'll be back on the gdb prompt, where you'd
issue the `bt' command (and copy all of its output as well as the few
lines that came after you "cont"inued.) Then close gdb, letting the
attached SIMH process die.

The crash info (along with the `bt' output) will probably give us an
idea where that bug is hidden.

MfG, JBG

-- 
      Jan-Benedict Glaw      jbglaw at lug-owl.de              +49-172-7608481
 Signature of:                            If it doesn't work, force it.
 the second  :                   If it breaks, it needed replacing anyway.
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