Linux kernel

Depending on what ISA you're using with gem5 the instructions for compiling a Linux kernel differ slightly.

Alpha

Currently we have a patch queue for Alpha that can be applied on top of a linux mercurial repository. This patch queue adds various debugging, performance, introspection capabilities and increases the number of simulated processors the Alpha implementation in gem5 can support from 4 to 64. To compile a new kernel for Alpha follow the directions below:

# First clone a copy of the mercurial linux repository
hg clone http://www.kernel.org/hg/linux-2.6

# Go to the .hg directory
cd linux-2.6/.hg

#Get a copy of the patches repository
hg clone http://repo.gem5.org/linux-patches patches

# Go back to the linux directory
cd ..

#Update the linux repository to a known working version
hg update v2.6.27
 
# Select the patches for 2.6.27
hg qselect 2.6.27
 
# Apply the patches to the repository
hg qpush -a

# Copy the default config file to .config
cp .config.m5 .config

# Build the kernel
make ARCH=alpha CROSS_COMPILE=/path/to/alpha/compiler/alpha-unknown-linux-gnu- vmlinux -j 4

I few minutes later a kernel will be compiled. You can use a newer version of m5, however you'll likely need to modify the config file and some of the patches slightly for it to work.