Mementos

A system that makes programs robust against frequent power loss on intermittently powered computers.

Currently implemented for the MSP430 family of processors.

The ASPLOS '11 paper describes Mementos in detail.

See license.txt for licensing terms.

Special Wolverine instructions

Use make -f Makefile.wolverine to build libmementos_fram.a, which you can link into your own programs.

Building and Installing

Note: Mementos now works on Wolverine (MSP430FRXXXX) hardware. Check out the wolverine branch!

Build and install LLVM and Clang using the CMake-style build. The rest of these instructions assume you have chosen to put your LLVM installation in /opt/llvm.

# download LLVM, Clang, compiler-rt to ~/tmp/llvm-3.5.0.src per LLVM's
# build instructions
...
$ cmake -DLLVM_TARGETS_TO_BUILD="X86;MSP430" -DCMAKE_BUILD_TYPE=Release \
        -DCMAKE_INSTALL_PREFIX=/opt/llvm ~/tmp/llvm-3.5.0.src

Install an MSP430 compiler toolchain such as mspgcc or gcc 4.9 (which includes an MSP430 backend in later releases). If you are using mspgcc, ensure that msp430-gcc is in your $PATH.
Clone the Mementos repository.

$ git clone git@github.com:spqr/mementos.git
$ export MEMENTOS="$PWD/mementos"

Build and install Mementos's LLVM passes:

$ cd "$MEMENTOS"/llvm
$ mkdir build && cd build
$ cmake -DLLVM_ROOT=/opt/llvm ..
$ make install

Configure Mementos's non-LLVM component:

$ cd "$MEMENTOS"
$ ./configure

Fetch the Mementos fork of MSPsim:

$ cd /opt/mementos/src
$ git clone git://github.com/ransford/mspsim.git mspsim
$ cd mspsim
$ ant

Now you can instrument your programs with Mementos and run them in MSPsim.

Dynamic symbol errors when running opt

On OS X (and possibly other OSes), if you get an error about a missing symbol when attempting to compiling programs with Mementos, you should edit /opt/mementos/src/llvm/tools/opt/Makefile and add the line KEEP_SYMBOLS := 1, then cd /opt/mementos/build/llvm && make install.

Mementos-izing a Program

By Mementosize a program, we mean instrument the program with energy checks called trigger points. By default, Mementos will build several variants of your program around several different instrumentation strategies: loop-latch instrumentation, function-return instrumentation, and timer-aided loop-latch instrumentation. We'll call these variants myfoo+latch, myfoo+return, and myfoo+timer. It additionally tries to build separate "plain" (uninstrumented) versions with clang and mspgcc.

Make sure the program is in a single .c file; let's call it e.g. myfoo.c.
Put the program in src/mementos (see below).
Build it against Mementos:

$ cd /opt/mementos/src/mementos
$ make TARGET=myfoo

If the build succeeds, you now have several executables representing different versions of your program. These are ready to run against mspsim.

Temporary link to download simulator based on MSPsim: [[http://www.cs.umass.edu/~ransford/mementos-downloads/mspsim-mementos-r571.tar.gz]]

Caveats

Things known not to work:

If you have your own TimerA interrupt defined, it will clash with the one Mementos tries to introduce in the myfoo+timer variant.

brutalsavage / mementos