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cspec

The C Semantics of seL4

l4v/spec/cspec/

This directory contains the entry point for the automatic translation of the seL4 source code into Isabelle/HOL.

The C semantics of the kernel is produced by first configuring and preprocessing the C sources for a specific platform and then parsing it into Isabelle using the C parser in l4v/tools/c-parser.

To inspect the output of this translation, build the image CSpec and interactively inspect the constants the parser has defined.

Top-Level Theory

The top-level theory file for this module is Kernel_C for the bare translation of seL4 into Isabelle, and KernelInc_C for additional automatic proofs about generated bitfield functions.

Building

The corresponding Isabelle sessions for this module are CKernel and CSpec. CSpec contains CKernel plus automated bitfield proofs.

To build the image, run the corresponding session in directory l4v/spec, e.g.:

make CSpec

This will also configure and preprocess the kernel sources.

Expect this build to take about 30 min on a modern machine and to require close to 4GB of memory. For further sessions building on top of CSpec, usually at least 16GB of main memory are required together with a 64-bit setup of Isabelle.

The target architecture may be specified by setting the L4V_ARCH environment variable. It determines both which configuration of seL4 is used, as well as indicating the architecture-specific definitions and proofs to use. The default architecture is ARM and will be selected if none is provided. See l4v/spec/cspec/c/Makefile for seL4 configuration details.

Remarks

To speed up interactive development, the bitfield code generator can be configured to skip the corresponding proofs and produce sorried (unproven) property statements only. To achieve this, set the environment variable SORRY_BITFIELD_PROOFS to TRUE.