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From: "Ard Biesheuvel" <ard.biesheuvel@linaro.org>
Date: Mon, 29 Apr 2019 10:17:17 +0200
Message-ID: <CAKv+Gu-kFo7DH+n=KR-CJR8ibbZ3wdmS=Z+RZw=wJhgCpYd9eA@mail.gmail.com>
Subject: Re: [edk2-devel] [edk2] [PATCH v2 edk2-platforms] Platform/ARM/Drivers: Add Nor Flash Driver
To: Leif Lindholm <leif.lindholm@linaro.org>
Cc: edk2-devel-groups-io <devel@edk2.groups.io>, Jagadeesh Ujja <jagadeesh.ujja@arm.com>, 
	Thomas Panakamattam Abraham <thomas.abraham@arm.com>
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On Mon, 29 Apr 2019 at 09:58, Leif Lindholm <leif.lindholm@linaro.org> wrot=
e:
>
> On Mon, Apr 29, 2019 at 08:52:46AM +0200, Ard Biesheuvel wrote:
> > > > > I am not sure if any other platform is using
> > > > > =E2=80=9CArmPlatformPkg/Drivers/NorFlashDxe=E2=80=9D and may requ=
ire block I/O and
> > > > > disk  I/O protocols
> > > > > if we remove =E2=80=9Csupport of block I/O and disk  I/O protocol=
s=E2=80=9D then we
> > > > > can share the common code easily.
> > > > >
> > > >
> > > > I see your point.
> > > >
> > > > The only reason you need block i/o and disk i/o is to use ordinary
> > > > partition and filesystem drivers. I guess Juno uses this for its ma=
gic
> > > > filesystem? If not, I'd be glad to get rid of it.
> > > >
> > > >
> > > Yes  "block i/o and disk i/o  of =E2=80=9CArmPlatformPkg/Drivers/NorF=
lashDxe=E2=80=9D
> > > driver is used even
> > > in RD-platforms(edk2-platforms/Platform/ARM/SgiPkg/)(and JUNO) to lis=
t
> > > partition. we don't want to break
> > > legacy and want to have separate
> > > "Platform/ARM/Drivers/StandaloneMmNorFlash/" driver.
> >
> > In that case, could we move the existing code into
> > edk2-platforms/Platform/ARM first? And then rip out the block i/o and
> > disk i/o parts from the common driver?
> >
> > Leif, any thoughts?
>
> I guess my only thought is what to do about RDKQemu? Probably is
> doesn't make any use of the special sauce, but need to verify?
>
> Then we conside stripping it out of the ARM platforms
> medium-term. It's one of the last bastions of "let's be different".
> Even if it should be kept around, surely it could be revamped to sit
> on top of a sane, generic NorFlashDxe?
>
> I mean, the actually relevant bit is basically
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/d=
rivers/mtd/afs.c,
> isn't it?
>
> +Thomas.
>

AIUI, these things are entirely separate. Exposing NOR flash via block
I/O and disk I/O permits the standard partition driver and FAT
filesystem driver to bind to it, so that you can have a standard FAT
ESP on NOR flash. I don't this is related at all to the BootMonFs
stuff