[Vm-beginners] A couple of vm beginner questions

[Eliot Miranda]

Hi Philip,

On Sat, Jan 12, 2019 at 1:56 PM Philip Bernhart <philip.bernhart at posteo.de>
wrote:

> Hi,
>
> I have a bunch of "beginner"(?) questions:
>
> 1. How to ensure that my local "stable" build from "stable"
>    sources corresponds to the "stable" vm binary published
>    on squeak.org? For example some time ago I build from the
>    stable tag 201807260206 (= commit
>    d1f3fb1c76ad72155d3becc8f9bed7d70e9485a9) which resulted in a
>    VM which somehow had some weird and hard to understand issues
>    with numbers corresponding in blaming the running smalltalk
>    implementation in my case cuis:
>    https://github.com/Cuis-Smalltalk/Cuis-Smalltalk-Dev/issues/145


Derive the version info from the VM via -version (Squeak) or --version
(Pharo).  This should give you something like:

5.0 64 bit Mac OS X built on Oct 20 2018 08:16:09 UTC Compiler: 4.2.1
Compatible Apple LLVM 7.3.0 (clang-703.0.31) [Production Spur 64-bit VM]
CoInterpreter VMMaker.oscog-eem.2461 uuid:
b3cd33f5-6309-43a1-b669-7a1805111f34 Oct 20 2018
StackToRegisterMappingCogit VMMaker.oscog-eem.2464 uuid:
0b1fa0a3-a781-4fd5-b1cf-1809796ccbbf Oct 20 2018
VM: 201810190412 https://github.com/OpenSmalltalk/opensmalltalk-vm.git
Date: Thu Oct 18 21:12:21 2018 CommitHash: 15341b5
Plugins: 201810190412 https://github.com/OpenSmalltalk/opensmalltalk-vm.git

then in your clone of opensmalltalk-vm checkout the commit (CommitHash
field above):

Aeolus.oscogvm.reference$ git checkout 15341b5
Note: checking out '15341b5'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by performing another checkout.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -b with the checkout command again. Example:

  git checkout -b <new-branch-name>

HEAD is now at 15341b5... CogVm source as per VMMaker.oscog-eem.2464

then make sure your development tools match the Compiler version info
(first line in the version info above) and build.

You can then return to the tip via $ git pull origin Cog

2. How to build the VM for a platform which has the dietlibc or a
>    different implementation of the standard C library?
>    I once tried to build it on alpine linux so to get
>    a minimal and small baseimage of it running to be able to use
>    it in within Docker containers without waiting 30 minutes for
>    the build, because of added sizes and complexities when relying
>    on a more "standard" base linux system (*cough* ubuntu *cough*).
>

I don't understand what its special about the libc.  What are the issues
here?  The convention we use is to create a build directory for the
particular host (e.g. build.macos64x64 is Mac OS X, 64-bit using x86_64),
and populate it with build directories for the dialects and configurations
you want (e.g. pharo.cog.spur, squeak.stack.spur).  So if you want to add a
configuration it should be easy to
- copy a directory tree from the most similar platform
- submit your build tree via a pull request


3. What is now the supposed "best practice" of adding functionality
>    to squeak? Say I want to add to it support for password hashing
>    using libsodium and the library blocks the VM when trying
>    to do more elaborate calls, so an async call would be much less
>    of a pain from the user perspective. So async calling in a
>    FFI library of that code or moving that into a VM plugin so
>    it's much wider supported?
>

Ah.  Now that is a long topic.  How much time do you have before you
urgently need a solution?  The right way is to use the ThreadedFFI but this
is still in prototype form.  It is something I will put energy into this
year but the solution won't be ready for months, and that's being
optimistic.  And we really need to gather a team together around the
threaded FFI to share the effort and maintain energy and focus.

A "quick hack" is exemplified by the style used in the Windows SocketPlugin
support; see platforms/win32/plugins/SocketPlugin/sqWin32NewNet.c.  The
support code manages a set of hidden threads to do lookups and there is a
pair pf primitives, one to submit a non-blocking lookup request, and
another to reap the request.  See e.g.

NetNameResolver class>>#primStartLookupOfName:
NetNameResolver class>>#primAddressLookupResult
NetNameResolver class>>#primAbortLookup

4. How to specialized VMs for special use cases? Like for example
>    I would want to build the VM for some architectures where there
>    is no binary around and which don't like or support any JIT
>    implementation. How do I correctly select the VM, configure and
>    build it and also can ensure that it works?
>

Look at the <dialect>.stack.<memorymanager> builds, for example
build.linux64ARMv8/squeak.stack.spur builds a StackInterpreter, which has
no JIT, for  64-bit Linux on ARMv8.  We don't yet have a JIT back end of
64-bit ARM.

That's probably already too much to be answered in one mail.
>

Cheers, and welcome!

_,,,^..^,,,_
best, Eliot
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