Re: [Xen-devel] [RFC 24/29] xen/arm: Don't use pl011 UART by default for early printk

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 30 April 2013 10:00, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:

On Mon, 2013-04-29 at 00:02 +0100, Julien Grall wrote:

> diff --git a/config/arm32.mk b/config/arm32.mk
> index f64f0c1..83a7767 100644
> --- a/config/arm32.mk
> +++ b/config/arm32.mk
> @@ -7,6 +7,17 @@ CONFIG_ARM_$(XEN_OS) := y
>  # Explicitly specifiy 32-bit ARM ISA since toolchain default can be -mthumb:
>  CFLAGS += -marm
>
> +# Xen early debugging function
> +# This is helpful if you are debbuging code that executes before the console
> +# is initialized.
> +# Note that selecting this option will limit Xen to a single UART
> +# definition. Attempting to boot Xen image on a different platform *will
> +# not work*, so this option should not be enable for Xens that are
> +# intended to be portable.
> +# Possible value:
> +#   - none: no early printk
> +#   - pl011: printk with PL011 UART
> +CONFIG_EARLY_PRINTK := none

I'm wondering if this is the right place for this "config", other than
the load address (which is also arguably not supposed to be here), they
are mostly per-platform variables rather than user focussed config
options.
This new option seems more akin to the debug=y or CONFIG_DTB_FILE
buildtime options, which are mostly contained xen/Makefile and
xen/arch/arm/Makefile etc.

I'm not really sure about this though -- the hypervisor doesn't really
have much in the way of user tunable CONFIG options -- anyone else have
any opinions?

I think we need to have a "high" level way to choose the early printk driver. The user

should not take care about the base address. Is .config is suitable for this kind of

options?

--

Julien Grall

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