On 10/7/2015 2:05 PM, Peter Maydell wrote: > On 7 October 2015 at 17:40, Mario Smarduch <m.smarduch@xxxxxxxxxxx> wrote: >> On 10/7/2015 12:07 AM, Peter Maydell wrote: >>> On 7 October 2015 at 01:32, Mario Smarduch <m.smarduch@xxxxxxxxxxx> wrote: >>>> Hi Peter, >>>> I noticed that icedcc, and 8250 don't work >>>> with DEBUG_LL early debug print. And the kernel dies if >>>> these are selected. Besides PL011 is there any other >>>> serial devices that can be used for early debug with Virt MM? >>>> Maybe some additional options are needed? >>> >>> PL011 and semihosting are the obvious choices for early >>> debug output. There's no 8250 in the virt board so that >>> definitely isn't going to work. We don't currently implement >>> the ICE DCC channel, though I think Edgar was considering >>> connecting it up to a chardev backend. >>> >>> Really though, I think the UART and semihosting should >>> be enough for whatever the guest wants to do in the way >>> of early debug. Why do you need more options? > >> No actually I was thinking of limiting choices to the ones that work for >> Virt MM during kernel config. But thought that maybe others may be >> supported through some options. Form me PL011 alone is enough. > > 8250 I think is what kvmtool uses, which is why that is a > permitted option. Not sure who's implementing ICE DCC > (though as I say QEMU might eventually). I see thanks for pointing that out. > > thanks > -- PMM > I came across the issue of selecting wrong UART for DEBUG_LL while trying to boot arm32 on arm64. ARCH_VIRT system type defaults for 'Kernel low-level debugging port' are not too clear. I'm wondering if it would make sense to add entries for virtual system types (like QEMU Virt or kvmtool virt) and enhance help section with possible UART_PHYS address, also set a default port. It appears like hard coding is going to be deprecated. This is not a major enhancement but when you're out of options and you just see a blank screen anything helps. Especially for virtual host where you may start suspecting the host system as well. Since I tripped over it, I took a closer look. Thanks, Mario _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
