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Standard Universe

Notes from Peter Keller's 2011-11-30 brain-dump.

libsyscall

The standard universe requires 'condorized' binaries, which are "statically-linked" binaries (see below for the standard universe definition thereof) created by condor_compile, which, despite the name, is a linker, rather than a compiler. It creates binaries with the API stack on the right. 


normal                condorized
---------------       ------------------
| application |       |  application   |
|             |       |   |------------|
|             |       |   | libsyscall |
---------------       |------------|   |
|    libc     |       |    libc    |   |
---------------       ------------------
|   kernel    |       |   kernel       |
---------------       ------------------
The interposition layer, libsyscall, comes before libc on the link line; the application thus calls its functions in preference to libc's. (Note that libsyscall does not override every libc function; only those necessary for checkpointing and/or remote I/O.)

When starting a standard universe job, the standard universe -specific shadow establishes a connection with the startd. This connection is inherited by the standard universe -specific starter, which in turn bequeaths it to the application (specifically, libsyscall). The starter's connection is used for startup, shutdown, and suspend/resume. All other communication to the shadow comes from libsyscall.

There may be machinery in libsyscall to make it signal-atomic.

"Statically-Linked"

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