On Fri, Oct 16, 2015 at 08:19:59PM -0700, Mario Smarduch wrote:
> When booting a VM using QEMU or Kvmtool there are no clear ways to 
> enable low level debugging for these virtual platforms. some menu port 
> choices are not supported by the virtual platforms at all. And there is no
> help on the location of physical and virtual addresses for the ports.
> This may lead to wrong debug port and a frozen VM with a blank screen.
> 
> This patch adds menu selections for QEMU and Kvmtool virtual platforms for 
> low 
> level kernel print debugging. Help section displays port physical and
> virutal addresses.
> 
> ARM reference models use the MIDR register to run-time select UART port 
> address 
> (for ARCH_VEXPRESS) based on A9 or A15 part numbers. Looked for a same 
> approach
> but couldn't find a way to differentiate between virtual platforms, something
> like a platform register.
> 
> Signed-off-by: Mario Smarduch <[email protected]>
> ---

I can't think of any better way to do this and I would be happy to see
this functionality in Linux, so:

Acked-by: Christoffer Dall <[email protected]>

>  arch/arm/Kconfig.debug | 22 ++++++++++++++++++++++
>  1 file changed, 22 insertions(+)
> 
> diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
> index a2e16f9..d126bd4 100644
> --- a/arch/arm/Kconfig.debug
> +++ b/arch/arm/Kconfig.debug
> @@ -1155,6 +1155,28 @@ choice
>                 This option selects UART0 on VIA/Wondermedia System-on-a-chip
>                 devices, including VT8500, WM8505, WM8650 and WM8850.
>  
> +     config DEBUG_VIRT_UART_QEMU
> +             bool "Kernel low-level debugging on QEMU Virtual Platform"
> +             depends on ARCH_VIRT
> +             select DEBUG_UART_PL01X
> +             help
> +               Say Y here if you want the debug print routines to direct
> +               their output to PL011 UART port on QEMU Virtual Platform.
> +               Appropriate address values are:
> +                     PHYS            VIRT
> +                     0x9000000       0xf8090000
> +
> +     config DEBUG_VIRT_UART_KVMTOOL
> +             bool "Kernel low-level debugging on Kvmtool Virtual Platform"
> +             depends on ARCH_VIRT
> +             select DEBUG_UART_8250
> +             help
> +               Say Y here if you want the debug print routines to direct
> +               their output to 8250 UART port on Kvmtool Virtual
> +               Platform. Appropriate address values are:
> +                     PHYS            VIRT
> +                     0x3f8           0xf80903f8
> +
>       config DEBUG_ICEDCC
>               bool "Kernel low-level debugging via EmbeddedICE DCC channel"
>               help
> -- 
> 1.9.1
> 
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Reply via email to