Re: [Xen-devel] [PATCH] xen/hvc-console: Make it work with HVM guests.

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Sat, Oct 26, 2013 at 09:27:08AM +0100, Ian Campbell wrote:
> On Fri, 2013-10-25 at 15:38 -0400, Konrad Rzeszutek Wilk wrote:
> > On Thu, Oct 24, 2013 at 05:43:54PM +0100, Ian Campbell wrote:
> > > But stepping back how/why is this function called on x86 when not
> > > running under Xen? Wouldn't the use have to be using console=hvc or
> > > earlyprintk=xen or something -- which strikes me as user error... IOW
> > > can we not just nuke the check
> > 
> > It shouldn't - ever. On x86 it is called from the early PV bootup code.
> > 
> > I occasionaly use it when developing/debugging and as such want it working
> > in HVM even during early bootup.
> 
> Does earlyprintk=ttyS0,cough not Just Work for HVM guests? That would
> avoid all of this stuff and assuming it works would be preferable IMHO.

It works OK. But this is an alternative avenue of using 'xen_raw_printk'
for both PV and HVM.

> 
> Anyway, if not, then given that the xen_cpuid_base case is entirely x86
> specific perhaps we can abstract this as something like:
> 
>       if (xen_arch_raw_console(str))
>               return
> 
>       dom0_write_console(...)
> 
> Then ARM:
>       #define xen_arch_raw_console 0
> and x86
>       static inline int xen_arch_raw_console(str)
>       {
>               if (xen_domain())
>                       return 0;
> 
>               /* Do the outb thing */
>               return 1;
>       }
> 
> This would also avoid the need for #ifdef x86 in the main function which
> Julien pointed out.

OK.
> 
> Ian.
> 

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