From b22853b2f4bdd1ed31d601ebd331083d67d40f11 Mon Sep 17 00:00:00 2001 From: Palmer Dabbelt Date: Tue, 13 Jun 2017 15:14:38 -0700 Subject: Add a SMP example This just prints "hello world" on two cores. It contains an example of how to initialize a multi-core system using IPIs, and a simple spin lock. --- software/smp/smp.c | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 software/smp/smp.c (limited to 'software/smp/smp.c') diff --git a/software/smp/smp.c b/software/smp/smp.c new file mode 100644 index 0000000..36c9db9 --- /dev/null +++ b/software/smp/smp.c @@ -0,0 +1,40 @@ +#include +#include +#include "atomic.h" +void write_hex(int, unsigned long); + +atomic_t tty_lock = ATOMIC_INIT(0); + +void get_lock(atomic_t *lock) +{ + while (atomic_xchg(lock, 1) == 1); + mb(); +} + +void put_lock(atomic_t *lock) +{ + mb(); + atomic_xchg(lock, 0); +} + +int secondary_main(int hartid) +{ + volatile int counter; + + while (1) { + get_lock(&tty_lock); + write(1, "hello world from hart ", 22); + char s[] = {'0', '\n', '\0'}; + s[0] += hartid; + write(1, s, 2); + put_lock(&tty_lock); + + for (counter = 0; counter < 10000 + 100*hartid; ++counter) + mb(); + } +} + +int main() +{ + return secondary_main(0); +} -- cgit v1.2.1-18-gbd029