Hi York, 2016-06-21 1:30 GMT+09:00 york sun <york....@nxp.com>: > On 06/19/2016 03:34 AM, André Przywara wrote: >> Hi, >> >> On 19/06/16 09:57, Masahiro Yamada wrote: >>> 2016-06-18 18:40 GMT+09:00 Linus Walleij <linus.wall...@linaro.org>: >>>> On Fri, Jun 17, 2016 at 2:51 PM, Masahiro Yamada >>>> <yamada.masah...@socionext.com> wrote: >>>> >>>>> There are two enable methods supported by ARM64 Linux; psci and >>>>> spin-table. The latter is simpler and easier to use for quick SoC >>>>> bring-up. >>>>> >>>>> So, I used the spin-table for my first ARMv8 SoC porting, but I >>>>> found its support in U-Boot was poor. It is true there exists a >>>>> code fragment for the spin code in arch/arm/cpu/armv8/start.S, >>>>> but I see some problems: >>>> >>>> Is part of the motivation for this approach to boot an ARMv8 system >>>> without using the ARM Trusted Firmware? >>>> >>>> Yours, >>>> Linus Walleij >>> >>> Yes, exactly. >>> >>> It would be the best choice >>> to switch over to PSCI with ATF in a long run, >>> but, I decided to use spin-table for the initial SoC bring-up >>> because of tight schedule. >> >> So if you don't have an ATF port ready, why not use U-Boot's PSCI >> implementation meanwhile? I think there are efforts underway to make >> PSCI enablement for random new boards a walk in the park (by making the >> PSCI support as generic as possible, CCing Chen-Yu for this). >> >> IIRC the spin-table boot method was just introduced to cope with cores >> that don't have EL3 and thus cannot provide PSCI services the normal way >> (and that don't want to or cannot sacrifice EL2 for that). >> So I am a bit wary of proliferating this SMP method. >> >> Wouldn't it be better to help making U-Boot's PSCI stack as easy to use >> as possible? I don't see technical reasons that adding PSCI support for >> a board should be harder or more involved than adding spin-table support >> - in the end you need to tell it about the SMP pen, maybe providing (or >> faking?) reset and shutdown for 0.2 compliance. >> > > We have a team working on PSCI for ARMv8. The patches are floating and > need some minor fix. With these patches, PSCI will be used instead of > spin-table. However, a trusted firmware (or other kind) is required. >
That's great. So, what should we do about this patch? I admit PSCI with ATF is the best way in the end, but I believe having a simpler alternative should not hurt. -- Best Regards Masahiro Yamada _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
