curr_cpu_apic_id() now works on old amd cpus

1 files changed, 21 insertions, 0 deletions

diff --git a/kernel/src/cpu/msr.c b/kernel/src/cpu/msr.c
new file mode 100644
index 0000000..75fc602
--- /dev/null
+++ b/kernel/src/cpu/msr.c
@@ -0,0 +1,21 @@
+#include <msr.h>
+
+uint64_t read_msr(uint32_t addr)
+{
+	uint64_t eax;
+	uint64_t edx;
+	uint64_t ecx = addr;
+
+	__asm__ volatile ("rdmsr;" : "=a"(eax), "=d"(edx) : "c"(ecx) :);
+
+	return (edx << 32) | eax;
+}
+
+void write_msr(uint32_t addr, uint64_t value)
+{
+	uint64_t eax = value & 0xFFFFFFFF;
+	uint64_t edx = value >> 32;
+	uint64_t ecx = addr;
+
+	__asm__ volatile ("wrmsr;" : : "a"(eax), "d"(edx), "c"(ecx) :);
+}