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FreeBSD FFI Oddity

8 September 2013

Periodically, I build the CogVM from source on FreeBSD. I've prevously mentioned that I had encountered some oddity with FFI on that platform. Still there today.

The following code crashes the VM/image:

| db |
db := SQLiteConnection fileNamed: '/tmp/x.db'.
db withResultForQuery: 'select * from a;'
  do: [ :result |
    result do: [ :row |
      Transcript show: row asString; cr ]].
db close.

The oddity is that one particular version of the SqueakFFIPrims plugin works. Several other versions that I've built all fail. Overwriting the failed versions of the plugin with the known-working one allows that particular crashing VM's FFI to work.

-rwxr-xr-x  1 root  wheel  77035 Oct 21  2012 ./4.0-2562/SqueakFFIPrims
-rwxr-xr-x  1 root  wheel  77035 Oct 21  2012 ./4.0-2586/SqueakFFIPrims
-rwxr-xr-x  1 root  wheel  74637 Nov 11  2012 ./4.0-2586/SqueakFFIPrims.broken
-rwxr-xr-x  1 root  wheel  77035 Oct 21  2012 ./4.0-2779/SqueakFFIPrims

The working one appears here three times. I'm running FreeBSD 8.3.

Deployment War Stories

28 October 2012

I used to run Squeak and subsequently Pharo on FreeBSD. I had the Smalltalk RFB server running within the image, and connected to the image via COTVNC (Chicken of the VNC), an OSX client. I ran Squeak/Pharo in a FreeBSD jail, and doing it this way kept the jail minimalist and tidy. No X stuff was installed.

Then I ran into some difficulty with FFI on CogVM on FreeBSD. (That's for another post.) And I was running FreeBSD 7, which EOLed. So I switched to Linux. Chose Debian 6 after trying out several distros. Similar setup as on FreeBSD: Minimalist LXC container, CogVM, RFB server in the same Pharo image that ran on FreeBSD.

Interestingly, neither COTVNC nor several other VNC clients (both within X on Linux and from OSX, including Java and native ones) worked in this setup: As far as I determined, the VNC connections were all failing because of incompatible encodings, and I tested quite a few combinations.

I wasn't interested in debugging too much, so I did the next simplest thing: Installed an Xvnc environment. So, instead of running an RFB server within Pharo, I had Pharo running within an X environment that was also a VNC server. And then all the VNC clients I was testing with worked. Not as tidy as I wanted, because now the LXC container had a whole bunch of X cruft, but hey, it was working.

But I really prefer FreeBSD. So after getting my production Linux server up and running, I went to investigate my FreeBSD CogVM FFI issue. And it turned out to be a process error on my part. I think. But that's for another post.

A note on my (fairly typical) setup: My development machine is an MBP. My development and pre-production FreeBSD and Linux servers all exist as VirtualBox or VMWare virtual machines on my MBP. The development servers have X, while the pre-production servers are meant to provide the canonical configuration for the production servers, so I run them without X, as much as possible. On FreeBSD, I have never had to run X in production. On Linux, I have the aforementioned Xvnc setup.

Anyhow, CogVM FFI FreeBSD was working again, in my development server running X. Next I tested it in my X-less pre-production server. When I invoked CogVM with "-headless", it said "cannot locate vm-display-X11" or words to that effect, even though said dynamic library was right there together with vm-display-null. I reckon that vm-display-X11 failed to locate an X environment, hence failed to load, hence the error message. Meaning, instead of -headless, I had to run -nodisplay.

So, CogVM ran -nodisplay, and COTVNC connected to it fine. Opened a workspace, typed some FFI-using code, selected the text with the mouse, pressed ESC. What's this? CogVM or Pharo crashed! PharoDebugLog recorded "SubclassResponsibility: NonInteractiveUIManager had the subclass responsibility to implement #newMenuIn:for:".

Hmmm. This didn't happen in Pharo 1.0 and 1.1, IIRC. Seems Pharo's random refactorings (heh, just kidding) changed how -nodisplay was managed between those versions and 1.4, the version I was testing.

After browsing a bit, looks like Pharo's graphical environment is managed by MorphicUIManager, but when invoked -nodisplay, even with a running RFB server, Pharo's graphical environment is managed by NonInteractiveUIManager.

One possibility to get this working is to install a minimal X environment, to run CogVM+Pharo -headless (with MorphicUIManager) instead of -nodisplay (with NonInteractiveUIManager).

But that isn't the simplest thing that could possibly work. What is? Copy & paste, of course. Specifically, I copied/pasted MorphicUIManager>>newMenuIn:for: into NonInteractiveUIManager. Ok, now pressing ESC brings up the context menu, "Do it" does, and output in the Transcript shows the expected FFI-related output.

Next I run my application's startup code in a workspace, one step of which is sending the "explore" message to the application's main instance, thus giving me a handle to said instance should I need to manipulate it, which is kinda the point of having VNC access into the image in the first place.

What's this? Crashed again! PharoDebugLog informs me "MessageNotUnderstood: NonInteractiveUIManager>>explorer:for:withLabel:" and "An attempt to use interactive tools detected, while in non-interactive mode".

Not so simple then...

(To be continued.)