From: Peng Fan <[email protected]> There is frequent start/shutdown operation in kernel reboot process. And at the end of kernel reboot, kernel will switch to use console output,saying imx_console_write on i.MX8MM.
imx_console_write will save/restore uart configuration. However before imx_console_write the UCR1_UARTEN already set to 0. when restore, it is also 0. Then when we runs into jailhouse disable, jailhouse write to uart will trigger errors. So let's add a check. However to hypervisor itself, there is still risk that kernel disable uart, whenh jailhouse is going to write data registers even with this patch applied. There is no good way to avoid such contention, the best way to avoid such issue is that use a different uart from Linux or remove `.type = JAILHOUSE_CON_TYPE_IMX,` from configs/arm64/imx8mm.c. Remove `.type = JAILHOUSE_CON_TYPE_IMX,` means jailhouse hypervisor will not output to uart, but you still could see jailhouse log by `cat /dev/jailhouse` Signed-off-by: Peng Fan <[email protected]> --- hypervisor/arch/arm-common/uart-imx.c | 4 ++++ inmates/lib/arm-common/uart-imx.c | 4 ++++ 2 files changed, 8 insertions(+) diff --git a/hypervisor/arch/arm-common/uart-imx.c b/hypervisor/arch/arm-common/uart-imx.c index 849f8fca..6485f36e 100644 --- a/hypervisor/arch/arm-common/uart-imx.c +++ b/hypervisor/arch/arm-common/uart-imx.c @@ -15,6 +15,8 @@ #define UTS 0xb4 #define UTXD 0x40 +#define UCR1 0x80 +#define UCR1_UARTEN (1<<0) #define UTS_TXEMPTY (1 << 6) static void uart_init(struct uart_chip *chip) @@ -29,6 +31,8 @@ static bool uart_is_busy(struct uart_chip *chip) static void uart_write_char(struct uart_chip *chip, char c) { + if ((mmio_read32(chip->virt_base + UCR1) & UCR1_UARTEN) != UCR1_UARTEN) + return; mmio_write32(chip->virt_base + UTXD, c); } diff --git a/inmates/lib/arm-common/uart-imx.c b/inmates/lib/arm-common/uart-imx.c index 984dc218..9cdf9089 100644 --- a/inmates/lib/arm-common/uart-imx.c +++ b/inmates/lib/arm-common/uart-imx.c @@ -39,6 +39,8 @@ #define UTS 0xb4 #define UTXD 0x40 +#define UCR1 0x80 +#define UCR1_UARTEN (1<<0) #define UTS_TXEMPTY (1 << 6) static void uart_imx_init(struct uart_chip *chip) @@ -53,6 +55,8 @@ static bool uart_imx_is_busy(struct uart_chip *chip) static void uart_imx_write(struct uart_chip *chip, char c) { + if ((mmio_read32(chip->base + UCR1) & UCR1_UARTEN) != UCR1_UARTEN) + return; mmio_write32(chip->base + UTXD, c); } -- 2.30.0 -- You received this message because you are subscribed to the Google Groups "Jailhouse" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/jailhouse-dev/20210323062536.3888-2-peng.fan%40nxp.com.
