From: ssnf Subject: [PATCH 0/6] vmd: improve 8254 PIT emulatiom To: tech@openbsd.org Cc: ssnf Date: Sat, 22 Aug 2026 19:02:41 +0000 This series of patches fixes several independent correctness bugs in vmd's 8254 PIT emulation. Guests that program the PIT according to the hardware interface expose cases where vmd's emulation differs from the 8254 behavior. Tested with a 9front guest under -current. Comments and tests are welcome. ssnf (6): vmd: store i8253 modes in register representation vmd: emulate i8253 square-wave counter correctly vmd: handle zero i8253 counter value as 65536 vmd: reset i8253 input latch on new counter writes vmd: only assert IRQ0 for i8253 channel 0 vmd: preserve i8253 counter load timestamp usr.sbin/vmd/i8253.c | 25 ++++++++++++++++--------- usr.sbin/vmd/i8253.h | 2 +- 2 files changed, 17 insertions(+), 10 deletions(-) -- 2.51.0