[U-Boot] [PATCH 0/6] ARMv7: Add HYP mode switching support

Christoffer Dall cdall at cs.columbia.edu
Sat Jun 1 01:49:59 CEST 2013


On Fri, May 31, 2013 at 08:36:12AM +0200, Andre Przywara wrote:
> On 05/31/2013 08:11 AM, Christoffer Dall wrote:
> > On Mon, May 06, 2013 at 03:17:44PM +0200, Andre Przywara wrote:
> >> (for GIT URL and Changelog see below)
> >>
> >> ARM CPUs with the virtualization extension have a new mode called
> >> HYP mode, which allows hypervisors to safely control and monitor
> >> guests. The current hypervisor (KVM and Xen) implementations
> >> require the kernel to be entered in that HYP mode.
> >>
> >> This patch series introduces a configuration variable
> >> CONFIG_ARMV7_VIRT which enables code to switch all cores into HYP
> >> mode. This is done automatically during execution of the bootm
> >> command (but could also be done earlier - U-Boot runs fine in HYP
> >> mode without MMU usage).
> >
> > I forget the u-boot specifics here, but if you boot over networking, for
> > example, does that eventually end up calling bootm or would Hyp mode not
> > be entered in this case?
> 
> Despite the naming "bootm" is eventually always called when booting 
> Linux, even bootz is a wrapper around this. Same with network boot. So 
> unless you show me a case where this isn't, I think this is fine.
> 
Cool, I have no idea, I just wanted to be sure.

Thanks,
-Christoffer


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