diff options
| author | Wei Hu <whu@FreeBSD.org> | 2023-03-14 15:49:33 +0000 |
|---|---|---|
| committer | Wei Hu <whu@FreeBSD.org> | 2023-03-18 07:07:54 +0000 |
| commit | 8ea7fa16d9fe5acb7d42a223efbfa23627aa5e0c (patch) | |
| tree | 03b442e28e5807748ec1b215ba19b0f3b6482530 | |
| parent | 927358dd98cb902160093e0dc0bac002d6b43858 (diff) | |
| download | src-8ea7fa16d9fe5acb7d42a223efbfa23627aa5e0c.tar.gz src-8ea7fa16d9fe5acb7d42a223efbfa23627aa5e0c.zip | |
uart: Don't change settings or throttle putc for Hyper-V
Azure setup does not like it when FreeBSD overrides the settings of the
UART device. When Hyper-V is detected, don't do this and also don't
throttle putc() output. This is a workaround for the early boot hang
of FreeBSD on Azure.
Tested on Azure, ESXi (VM with serial port), and SG-8200
PR: 264267
Reviewed by: kevans, whu
Tested by: whu
Obtained from: Rubicon Communications, LLC (Netgate)
MFC after: 2 weeks
Sponsored by: Rubicon Communications, LLC (Netgate)
| -rw-r--r-- | sys/dev/uart/uart_dev_ns8250.c | 20 |
1 files changed, 13 insertions, 7 deletions
diff --git a/sys/dev/uart/uart_dev_ns8250.c b/sys/dev/uart/uart_dev_ns8250.c index 475ab5d4425e..2c44e9e34b8b 100644 --- a/sys/dev/uart/uart_dev_ns8250.c +++ b/sys/dev/uart/uart_dev_ns8250.c @@ -249,6 +249,10 @@ ns8250_param(struct uart_bas *bas, int baudrate, int databits, int stopbits, int divisor; uint8_t lcr; + /* Don't change settings when running on Hyper-V */ + if (vm_guest == VM_GUEST_HV) + return (0); + lcr = 0; if (databits >= 8) lcr |= LCR_8BITS; @@ -374,9 +378,11 @@ ns8250_putc(struct uart_bas *bas, int c) { int limit; - limit = 250000; - while ((uart_getreg(bas, REG_LSR) & LSR_THRE) == 0 && --limit) - DELAY(4); + if (vm_guest != VM_GUEST_HV) { + limit = 250000; + while ((uart_getreg(bas, REG_LSR) & LSR_THRE) == 0 && --limit) + DELAY(4); + } uart_setreg(bas, REG_DATA, c); uart_barrier(bas); } @@ -532,15 +538,15 @@ ns8250_bus_attach(struct uart_softc *sc) #endif if (!resource_int_value("uart", device_get_unit(sc->sc_dev), "flags", &ivar)) { - if (UART_FLAGS_FCR_RX_LOW(ivar)) + if (UART_FLAGS_FCR_RX_LOW(ivar)) ns8250->fcr |= FCR_RX_LOW; - else if (UART_FLAGS_FCR_RX_MEDL(ivar)) + else if (UART_FLAGS_FCR_RX_MEDL(ivar)) ns8250->fcr |= FCR_RX_MEDL; - else if (UART_FLAGS_FCR_RX_HIGH(ivar)) + else if (UART_FLAGS_FCR_RX_HIGH(ivar)) ns8250->fcr |= FCR_RX_HIGH; else ns8250->fcr |= FCR_RX_MEDH; - } else + } else ns8250->fcr |= FCR_RX_MEDH; /* Get IER mask */ |