diff mbox series

[v1,2/5] ppc: Raise decrementer IRQ on zero write

Message ID 20260827155310.7223-3-kirill@korins.ky
State New
Headers show
Series mac99: Boot OpenBSD/macppc | expand

Commit Message

Kirill A. Korinsky Aug. 27, 2026, 3:50 p.m. UTC 
OpenBSD writes zero to an edge triggered decrementer, then enters idle
expecting its interrupt. QEMU defers the already due edge to a timer at
the current virtual time, leaving the guest stalled.

Signed-off-by: Kirill A. Korinsky <kirill@korins.ky>
---
 hw/ppc/ppc.c | 1 +
 1 file changed, 1 insertion(+)
diff mbox series

Patch

diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c
index b123b4cc1c..d99e47d532 100644
--- a/hw/ppc/ppc.c
+++ b/hw/ppc/ppc.c
@@ -885,6 +885,7 @@  static void __cpu_ppc_store_decr(PowerPCCPU *cpu, int64_t now, uint64_t *nextp,
      * an edge interrupt, so raise it here too.
      */
     if (((flags & PPC_DECR_UNDERFLOW_LEVEL) && signed_value < 0) ||
+        ((flags & PPC_DECR_UNDERFLOW_TRIGGERED) && value == 0) ||
         ((flags & PPC_DECR_UNDERFLOW_TRIGGERED) && signed_value < 0
           && signed_decr >= 0)) {
         (*raise_excp)(cpu);