On Mon, Nov 09, 2015 at 08:19:48AM -0700, Stephen Warren wrote: > On 11/09/2015 07:36 AM, Thierry Reding wrote: > >On Wed, Oct 28, 2015 at 11:59:04AM -0600, Stephen Warren wrote: > >>On 10/18/2015 10:57 PM, Alexandre Courbot wrote: > >>>T210's GPU secure firmware loading requires a write-protected region > >>>to be set up. > >>> > >>>This patch reserves the upper 256KB of RAM as the WPR region and locks > >>>it so the kernel can initiate secure firmware loading. > >> > >>On T210, it's the responsibility of nvtboot (which runs before U-Boot) to > >>set up any and all carve-outs. This code should not be necessary, and indeed > >>I expect the registers it touches can't actually be programmed from U-Boot, > >>which runs in non-secure mode after WPR is already locked. > > > >Can we document this assumption somewhere? It's entirely possible that > >someone might want to run U-Boot without nvtboot > > That's not currently a supported use-case. Isn't the whole point of open-source for people to be able to do all the things that aren't supported? > >, in which case nvtboot > >would still need to be responsible for setting this up. > > I assume s/nvtboot/whatever other bootloader is in use/? Right, I was going to write U-Boot here, but that's obviously only true if U-Boot is still running in secure mode. Otherwise, yes, it'd be what- ever is the other bootloader being used. > >Or if it isn't > >we could still point at some location where the interactions between a > >first stage bootloader and U-Boot are documented. > > > >Do we have a document of this kind already? > > The L4T U-Boot source code:-) There's a bunch of things that even the L4T U-Boot doesn't document. The fact that it doesn't initialize the SMMU or WPR doesn't indicate that it is something that a first stage bootloader needs to do. Thierry
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