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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