Re: [Xen-devel] Re: [PATCH 2/3] xen/granttable: Grant tables V2 implementation

[Ian Campbell <Ian.Campbell@citrix.com>]

On Fri, 2011-11-18 at 13:52 +0000, Konrad Rzeszutek Wilk wrote:
> > > +                       xen_raw_printk(str);
> > > +                       panic(str);
> > 
> > I expect you've just copied this style from elsewhere but I really
> > dislike this duplication of prints. If panic is not useful here we
> > really ought to address that at the root instead of going around
> > patching things to print every panic message twice. I thought
> > earlyprintk was supposed to solve this problem. Perhaps a generic
> > early_panic_print could be added to the panic code?
> 
> We are using this combo in swiotlb-xen and as well in the xen pci.
> We could declere a 'xen_raw_panic' that would do the job?
> 
> The problem is that panic() uses the "late" printk mechanism (so
> it goes through the buffer that ends up not beign flushed) and the
> panic never sees the light.

So lets fix that instead of working around it...

>  The 'xen_raw_printk' is synchronous..
> 
> But I wonder if the panic surfaces if 'earlyprintk=xen' is used?
> At which point it might be that the those extra xen_raw_printk
> become pointless?

I think panic's do come out with earlyprintk (unless they are truly
super early).

Ian.