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Release secondary cores from WFI (wait for interrupt) by sending them

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an IPI.

This does not work however yet in QEMU. As a temporary workaround set
software interrupt pending bit manually on a local core to ensure WFI
doesn't halt the hart.

This is required to smpboot in QEMU.

Sponsored by:	DARPA, AFRL
This commit is contained in:
Ruslan Bukin 2018-06-12 16:47:33 +00:00
parent 4fe984fdae
commit f2e299880a
1 changed files with 14 additions and 0 deletions
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14
sys/riscv/riscv/mp_machdep.c
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@ -181,6 +181,7 @@ riscv64_cpu_attach(device_t dev)
static void
release_aps(void *dummy __unused)
{
uintptr_t mask;
int cpu, i;
if (mp_ncpus == 1)
@ -191,6 +192,14 @@ release_aps(void *dummy __unused)
atomic_store_rel_int(&aps_ready, 1);
/* Wake up the other CPUs */
mask = 0;
for (i = 1; i < mp_ncpus; i++)
mask |= (1 << i);
sbi_send_ipi(&mask);
printf("Release APs\n");
for (i = 0; i < 2000; i++) {
@ -217,6 +226,11 @@ init_secondary(uint64_t cpu)
pcpup = &__pcpu[cpu];
__asm __volatile("mv gp, %0" :: "r"(pcpup));
/* Workaround: make sure wfi doesn't halt the hart */
intr_disable();
csr_set(sie, SIE_SSIE);
csr_set(sip, SIE_SSIE);
/* Spin until the BSP releases the APs */
while (!aps_ready)
__asm __volatile("wfi");