linux-kernel - Re: [PATCH 2/8] x86/head: Refactor 32-bit pgtable setup

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Date:   Fri, 2 Dec 2016 17:08:55 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, david.vrabel@...rix.com,
        JGross@...e.com, roger.pau@...rix.com,
        linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org,
        x86@...nel.org, Matt Fleming <matt@...eblueprint.co.uk>
Subject: Re: [PATCH 2/8] x86/head: Refactor 32-bit pgtable setup


* Boris Ostrovsky <boris.ostrovsky@...cle.com> wrote:

> On 12/02/2016 04:45 AM, Ingo Molnar wrote:
> > * Boris Ostrovsky <boris.ostrovsky@...cle.com> wrote:
> >
> >> On 10/31/2016 08:33 AM, Boris Ostrovsky wrote:
> >>>
> >>> On 10/14/2016 02:05 PM, Boris Ostrovsky wrote:
> >>>> From: Matt Fleming <matt@...eblueprint.co.uk>
> >>>>
> >>>> The new Xen PVH entry point requires page tables to be setup by the
> >>>> kernel since it is entered with paging disabled.
> >>>>
> >>>> Pull the common code out of head_32.S and into pgtable_32.S so that
> >>>> setup_pgtable_32 can be invoked from both the new Xen entry point and
> >>>> the existing startup_32 code.
> >>>
> >>> Ping to x86 maintainers.
> >> Pinging again.
> >>
> >> I will be re-sending this series at some point (it has been delayed by
> >> some hypervisor changes that will be needed) but I'd like to hear from
> >> x86 maintainers whether this will be acceptable before I post this again.
> > Could this be done in C?
> 
> I suppose it could be, I haven't thought about it.
> 
> The goal here was to simply make existing startup code available to others (Xen 
> guest) without changes. Are you suggesting to build page tables in C for the Xen 
> guest only or to make startup_32 call new C code as well?

My suggestion would be to transform the factored out assembly code to C.

Thanks,

	Ingo