Hi Stephen, On 28 July 2015 at 10:05, Stephen Warren <swar...@wwwdotorg.org> wrote: > On 07/28/2015 09:50 AM, Simon Glass wrote: >> >> Hi Stephen, >> >> On 28 July 2015 at 09:44, Stephen Warren <swar...@wwwdotorg.org> wrote: >>> >>> On 07/28/2015 09:33 AM, Simon Glass wrote: >>>> >>>> >>>> Hi, >>>> >>>> On 27 July 2015 at 11:45, Stephen Warren <swar...@wwwdotorg.org> wrote: >>>>> >>>>> >>>>> From: Thierry Reding <tred...@nvidia.com> >>>>> >>>>> For 64-bit ARM SoCs we rely on non-U-Boot code to bring up the CPU in >>>>> AArch64 mode so that we don't need the SPL. Non-cached memory is not >>>>> implemented (yet) for 64-bit ARM. >>>>> >>>>> Signed-off-by: Thierry Reding <tred...@nvidia.com> >>>>> Signed-off-by: Tom Warren <twar...@nvidia.com> >>>>> Signed-off-by: Stephen Warren <swar...@nvidia.com> >>>>> --- >>>>> include/configs/tegra-common.h | 4 ++++ >>>>> 1 file changed, 4 insertions(+) >>>> >>>> >>>> >>>> What does start up the CPU? Is this something that will be implemented >>>> in SPL later? >>> >>> >>> >>> At least initially, the plan is to use a separate bootloader on the boot >>> CPU >>> (was named AVP, but got renamed to BPMP lite in Tegra210). It's vaguely >>> possible that U-Boot SPL support will exist in the future, but I'm not >>> sure. >> >> >> Ah OK. Where does that live? I think SPL would be better. > > > We haven't yet worked out the logistics of how to release it. I expect it > will be a little while yet. > > As an aside, I don't think SPL is the right mechanism at least for new Tegra > chips, although using the U-Boot code base on the boot CPU might be > reasonable, and is something we might look at after we've got the first > round SW stack up. The boot CPU and main CPU complex have always been > different CPUs and even ARM architectures. While we were able to hack around > this with Tegra124 and earlier since they were both 32-bit ARM, so the same > compiler and variable sizes etc. could be used, this likely isn't possible > on Tegra210 and later, since the boot CPU is 32-bit ARM and the main CPU > complex is 64-bit ARM. It'd be better to build two completely separate > builds of U-Boot for the two CPU types, and then combine them together > during the flash image generation process.
Sounds reasonable. In a way this is similar to SPL works, except I think you are saying that there would be no need for SPL to load U-Boot since they would be packaged together, as now. My understanding is that the motivation for having SPL at all with Tegra was these CPU differences. So from that POV I suppose Tegra 210 isn't any different. Regards, Simon _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
