Re: [Xen-devel] [PATCH V2 07/33] xen/arm: Create a hierarchical device tree

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2013-05-08 at 16:15 +0100, Julien Grall wrote:
> On 05/08/2013 02:41 PM, Ian Campbell wrote:
> 
> > On Wed, 2013-05-08 at 14:34 +0100, Julien Grall wrote:
> >>> Which only leaves ones which are both? How many are these? I'm inclined
> >>> towards suggesting that if they are debug prints which are disabled by
> >>> default and require a recompile to enable then the person doing the
> >>> debugging can select whether they care about early or late messages by 
> >>> #define-ing DEBUG or EARLY_DEBUG or both as required.
> >>
> >> We can't choose at compile time. Early printk function is in init code
> >> section. So at the end of boot the function will disappear.
> > 
> > Oh, right.
> > 
> > Perhaps something could be conditional on system_state =
> > SYS_STATE_active, this happens not long before we discard the initial
> > sections.
> 
> 
> I think it's too late. If we use early_printk until this stage, we will
> lose some usefull debug when early printk is disabled (ie most of the time).
> 
> How about adding the missing system_state = SYS_STATE_boot just after
> console_init_preirq? Early printk will only be used when system_state ==
> SYS_STATE_early_boot.

I think this is a common thing so it'd need wider discussion.

> >> Device tree function could be called after the end of the boot. For the
> >> moment it's not the case.
> >>
> >> The best solution would be: early_printk is directly handled in console
> >> as linux does.
> > 
> > That does sound best.
> 
> 
> I will send a patch later for this.

Does that make the above moot?

Ian.


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