how hard is it to rewrite code in a .beam file?
Fri Aug 27 15:53:42 CEST 2010
I'd appreciate some wisdom about writing a .beam -> .beam transform
which lets me load a few known (i.e. not every possible) .beam files
compiled with R10B into an R13B04 VM.
I've looked at beam_load.c and beam_disasm.erl, they seem like
reasonable starting points. Anything else I should look at? Am
I doomed to fail, or do I have a sporting chance? Kostis? Björn? Tony?
I want to do this because upgrades on my embedded systems work roughly
1. Unpack a release file
2. Run gth_install.beam on the freshly unpacked release
This works fine until someone tries to downgrade from a modern release,
which uses R13B04, to an old release, which uses R10B:
=ERROR REPORT==== 27-Aug-2010::15:07:03 ===
beam/beam_load.c(1730): Error loading function gth_install:make_nand_symlinks/1: op m_plus p y i r:
please re-compile this module with an R13B04 compiler
I should have heeded warnings about efforts being made to preserve .beam
compatibility for two major OTP versions only. But I didn't. Duh.
I have a few ideas about how to extricate myself from this,
e.g. running multiple VMs at the same time or providing new versions
of the old .beams, but the .beam->.beam seems fun and neat, given
that I only have to make it work for a handful of versions of one module.
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