[PATCH v5 05/13] xen/arm,arm64: move Xen initialization earlier
Ian Campbell
Ian.Campbell at citrix.com
Fri Sep 6 04:58:59 EDT 2013
On Thu, 2013-09-05 at 17:59 +0100, Stefano Stabellini wrote:
> On Thu, 5 Sep 2013, Catalin Marinas wrote:
> > On Thu, Aug 29, 2013 at 07:32:26PM +0100, Stefano Stabellini wrote:
> > > Move Xen initialization earlier, before any DMA requests can be made.
> > >
> > > Signed-off-by: Stefano Stabellini <stefano.stabellini at eu.citrix.com>
> >
> > I guess you should cc the corresponding maintainers here.
>
> Thanks for the reminder, I'll do that.
>
>
> > > arch/arm/include/asm/xen/hypervisor.h | 8 ++++++++
> > > arch/arm/kernel/setup.c | 2 ++
> > > arch/arm/xen/enlighten.c | 21 ++++++++++++++-------
> > > arch/arm64/kernel/setup.c | 2 ++
> > > 4 files changed, 26 insertions(+), 7 deletions(-)
> >
> > [...]
> >
> > > --- a/arch/arm64/kernel/setup.c
> > > +++ b/arch/arm64/kernel/setup.c
> > > @@ -53,6 +53,7 @@
> > > #include <asm/traps.h>
> > > #include <asm/memblock.h>
> > > #include <asm/psci.h>
> > > +#include <asm/xen/hypervisor.h>
> > >
> > > unsigned int processor_id;
> > > EXPORT_SYMBOL(processor_id);
> > > @@ -267,6 +268,7 @@ void __init setup_arch(char **cmdline_p)
> > > unflatten_device_tree();
> > >
> > > psci_init();
> > > + xen_early_init();
> >
> > So Xen guests don't have any hope for single Image? Basically you set
> > dma_ops unconditionally in xen_early_init(), even if the kernel is not
> > intended to run under Xen.
>
> That should not happen: if we are not running on Xen xen_early_init
> returns early, before calling xen_mm_init.
x96 has a call to init_hypervisor_platform() at approximately this
location, which detects and calls the init function for any of Xen, KVM,
hyperv and vmware. I guess only Xen and KVM are currently relevant on
Linux ARM(64), so perhaps adding similar infrastructure on ARM would be
overkill at this point. I don't know if KVM needs such an early C-land
hook, I suppose it needs it even earlier so it can set up the hyp mode
trampoline from head.S?
Ian.
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