From: Alexander Kurz <akurz@blala.de>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: barebox@lists.infradead.org
Subject: Re: [PATCH] bootm: dont use internal oftree fallback by default
Date: Mon, 5 Dec 2016 11:49:24 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.00.1612051145090.13323@blala.de> (raw)
In-Reply-To: <20161205082919.vbqtltxd43jw4qvj@pengutronix.de>
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On Mon, 5 Dec 2016, Uwe Kleine-König wrote:
> On Fri, Dec 02, 2016 at 10:46:38AM +0100, Lucas Stach wrote:
> > Am Donnerstag, den 01.12.2016, 19:55 +0100 schrieb Alexander Kurz:
> > > Booting via bootm offers several methods to load oftree data. When no
> > > dedicated oftree image is provided, barebox checks for the presence of
> > > its own internal oftree, assuming it as a good choice for boot.
> > >
> > > This fallback method breaks the usecase when a modern OF-based barebox
> > > is used to boot a legacy ATAG dependent non OF based vendor provided kernel
> > > (e.g. ATAGs will be switched off).
> > > Unfortunately those kernels are being still actively shipped today.
> > >
> > > Change barebox according to the principle of least surprise: when no
> > > oftree data is proactively configured, then perform a non-oftree boot.
> > > Make the fallback-use of the barebox internal oftree an opt-in feature.
> > >
> > > Note: this will break boards where the boot process relied on this feature,
> > > e.g.: oftree based barebox plus oftree based kernel without an explicit
> > > given dts. For those boards global.bootm.internal_oftree_fallback=1 should
> > > be set.
> > >
> > The least surprise on a modern oftree based kernel is that the firmware
> > (Barebox) provides the DT, if there isn't an explicit override.
> >
> > So NACK on the patch in it's current form. If you have a board where you
> > know that the kernel doesn't play along, you may reverse this patch so
> > that you can set global.bootm.no_internal_oftree=1 in your board code.
>
> Ack for the NAck. And AFAIK you can already today just do
>
> oftree -f
>
> before calling bootm to discard the internal dtb which should make
> barebox fall back to ATAG.
After flushing the DT, ATAGs get passed during boot,
this makes my patch obsolete now.
Thank you very much,
Alexander
>
> Best regards
> Uwe
>
> --
> Pengutronix e.K. | Uwe Kleine-König |
> Industrial Linux Solutions | http://www.pengutronix.de/ |
>
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next prev parent reply other threads:[~2016-12-05 10:53 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-01 18:55 Alexander Kurz
2016-12-02 9:46 ` Lucas Stach
2016-12-05 8:29 ` Uwe Kleine-König
2016-12-05 10:49 ` Alexander Kurz [this message]
2016-12-05 10:36 ` Alexander Kurz
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