Re: [Suggestion] arch: arm64: xen: "ln -s" the paravirt.h fromarm.

From: Stefano Stabellini
Date: Tue Jun 25 2013 - 11:55:08 EST


On Tue, 25 Jun 2013, Catalin Marinas wrote:
> On Mon, Jun 24, 2013 at 05:50:46PM +0100, Stefano Stabellini wrote:
> > On Mon, 24 Jun 2013, Stefano Stabellini wrote:
> > > On Mon, 24 Jun 2013, Chen Gang wrote:
> > > > Hello Maintainers:
> > > >
> > > > if 'CONFIG_XEN'
> > > >
> > > > CC arch/arm64/xen/../../arm/xen/enlighten.o
> > > > arch/arm64/xen/../../arm/xen/enlighten.c:19:26: fatal error: asm/paravirt.h: No such file or directory
> > > >
> > > > The related .config file for next-20130624 is in attachment.
> > > >
> > > >
> > > > If "ln -s ../../../arm/include/asm/paravirt.h paravirt.h", it can pass
> > > > compiling, but I do not know how to make a patch for it ("ln -s ..."),
> > > > Do we have another more suitable ways for it (or another fixing ways) ?
> > > >
> > > > Welcome any suggestions or completions.
> > >
> > > The problem is caused by:
> > >
> > > commit 3a885582a366caf868b0782041c44854ff4c3568
> > > Author: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> > > Date: Wed May 29 10:56:34 2013 +0000
> > >
> > > xen/arm: account for stolen ticks
> > >
> > > that is in my tree for linux-next (even though I have not received any
> > > replies from the ARM maintainers so I don't know when and if it is going
> > > to go upstream).
> > >
> > > I think that the best thing to do would be to add a couple of ifdef
> > > CONFIG_PARAVIRT in arch/arm/xen/enlighten.c. I'll add them to my tree.
> >
> > Actually now that we have XEN support under arm64, we can just introduce the
> > same pv_time_op struct and paravirt header that this patch
> >
> > http://marc.info/?l=linux-arm-kernel&m=136992435301890&w=2
> >
> > is introducing under arm.
>
> I'm not sure whether I replied to your Xen pull request but the patches
> have been merged into my 'upstream' branch on git.kernel.org and they'll
> be going in for 3.11-rc1.

Great, thanks!


> > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> > index 19c1cde..47bd26b 100644
> > --- a/arch/arm64/Kconfig
> > +++ b/arch/arm64/Kconfig
> > @@ -207,6 +207,25 @@ config FORCE_MAX_ZONEORDER
> > default "14" if (ARM64_64K_PAGES && TRANSPARENT_HUGEPAGE)
> > default "11"
> >
> > +config PARAVIRT
> > + bool "Enable paravirtualization code"
> > + ---help---
> > + This changes the kernel so it can modify itself when it is run
> > + under a hypervisor, potentially improving performance significantly
> > + over full virtualization.
> > +
> > +config PARAVIRT_TIME_ACCOUNTING
> > + bool "Paravirtual steal time accounting"
> > + select PARAVIRT
> > + default n
>
> No need for "default n".
>
> If you want, I can apply this patch on top (or send me another pull
> request but don't rebase your original Xen branch which I merged).

Thanks, but unfortunately the corresponding arm part of this patch
(linked above) didn't manage to get enough reviews and acks.
I might as well send another iteration of "CONFIG_PARAVIRT and stolen
ticks accounting" with this change in it.
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