On Mon, Oct 29, 2018 at 06:46 PM, Chen, Jason CJ wrote:

After change vuart irq from 4 to 6, the SOS kernel config need enable CONFIG_SERIAL_8250_DETECT_IRQ,

Hi Jason,

Thanks for your reply. Of course I made sure this option was set in my .config file.
> grep CONFIG_SERIAL_8250_DETECT_IRQ kernel_config_uefi_sos
> CONFIG_SERIAL_8250_DETECT_IRQ=y

Moreover this option is set by default in the kernel_config_uefi_sos file in the acrn_kernel repository and I didn't change it.
However linux keeps choosing IRQ 4 for uart0, ...
I just recompiled everything (of course with acrn COM1_IRQ set to 6 and CONFIG_SERIAL_8250_DETECT_IRQ=y) and I still get in the boot trace:

> ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A

Last Friday, I even changed the default configuration in arch/x86/include/asm/serial.h

{ .uart = 0,    BASE_BAUD,    0x3F8,    6,    STD_COMX_FLAGS    }, /* ttyS0 */

but still got in my traces

> ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A

My opinion is that something makes linux believe the uart is really on IRQ 4...

Hi, Joe,

Your information make me a little confuse, if we enabled irq auto detection, either the port could detect the real irq as 6, or the port could not detect the irq, then irq will be set to 0.

Thanks,
Joe