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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Fri, 15 May 2020 17:41:37 +0200
Message-ID: <CAK8P3a1d-9B86uXxkZnDGf7u-2Vf9fCrUgWQ9HGNEcf3--Yg5w@mail.gmail.com>
Subject: Re: ARM: static kernel in vmalloc space
To:     Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc:     afzal mohammed <afzal.mohd.ma@gmail.com>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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On Fri, May 15, 2020 at 1:40 AM Russell King - ARM Linux admin
<linux@armlinux.org.uk> wrote:
> On Thu, May 14, 2020 at 11:12:01PM +0200, Arnd Bergmann wrote:
> > On Thu, May 14, 2020 at 6:25 PM Russell King - ARM Linux admin
> > <linux@armlinux.org.uk> wrote:
> > > On Thu, May 14, 2020 at 02:41:11PM +0200, Arnd Bergmann wrote:
> > > > On Thu, May 14, 2020 at 1:18 PM afzal mohammed <afzal.mohd.ma@gmail.com> wrote:
> > I expected the non-aliasing VIPT caches to work the same as PIPT, can
> > you clarify if there is something to be aware of for those? I see that some
> > ARMv8 chips and most ARMv6 chips (not OMAP2 and Realview) are
> > of that kind, and at we clearly don't want to break running on ARMv8 at
> > least.
>
> There are some aliasing VIPT implementations on ARMv6, but I don't
> remember how common.

I thought it was only realview-pb and omap2, but it seems there
are more, at least ast2500 is an important example.

I could not find information about integrator-cp and picoxcell.
For reference, this is a list of the arm11 chips we currently support,
with the aliasing dcache ones marked '*':

* ast2500: armv6k, arm1176, ??KB aliasing VIPT
  bcm2835: armv6k, arm1176, 16KB non-aliasing VIPT
  cns3xxx: armv6k, arm11mpcore, 32kb PIPT
  imx3: armv6, arm1136r0, 16kb non-aliasing VIPT
  integrator CM1136JF-S core module: arm1136r?, 16kb non-aliasing VIPT
? integrator CTB36 core tile: arm1136r?, ???
  ox820: armv6k, arm11mpcore, ??KB PIPT
* omap2: armv6, arm1136r0, 32kb aliasing VIPT
? picoxcell: armv6k, arm11??
* realview-pb1176: armv6k, arm1176, 32kb aliasing VIPT
  realview-eb with 1176 core tile: armv6k, 16kb non-aliasing VIPT
  realview-eb with 11mpcore core tile: armv6k, 32kb PIPT
  s3c64xx: armv6k, arm1176, 16kb non-aliasing VIPT
  wm8750: armv6k, arm1176: 16kb non-aliasing VIPT

           Arnd