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Re: [suspend/resume] Debugging via console

On Sun, May 04, 2008 at 07:13:35PM +0200, Jean-Yves Migeon wrote:
> Manuel Bouyer wrote:
> >Yes, the proper way to do this is to use HYPERVISOR_console_io().
> >There are XENPRINTK macros that already do this in the sources
> >(or you can call printk directly). As you said, this requires a debug
> >hypervisor, and a serial console (the NetBSD xenkernel3 package provides
> >a debug hypervisor).
> >  
> Hmm, I think I already know the answer, anyway: for laptops without 
> serials, there is no way to use console_io() for domUs then?

There may be some boot option that allow the hypervisor to not release
the VGA console, and so keep console_io() from working even once the
dom0 has booted. But then you'll have very limited console capabilities
in dom0.

It's possible that even if the console_io() doesn't appear on the VGA console,
it's keep in xen's message buffer and can be seen with xm dmesg. I've
never tried this though.

> Might it work with usb/rs232 converters? (I am not very confident on 
> grub's capability of handling such a device, but why not...)

Not only grub won't handle it, but the hypervisor won't either.

Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference

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