On Mon, Jun 27, 2016 at 07:31:05PM +0900, Masahiro Yamada wrote:
There are two enable methods supported by ARM64 Linux; psci and spin-table. The latter is simpler and helpful for quick SoC bring up. My main motivation for this patch is to improve the spin-table support, which allows us to boot an ARMv8 system without the ARM Trusted Firmware.
Currently, we have multi-entry code in arch/arm/cpu/armv8/start.S and the spin-table is supported in a really ad-hoc way, and I see some problems:
We must hard-code CPU_RELEASE_ADDR so that it matches the "cpu-release-addr" property in the DT that comes from the kernel tree.
The Documentation/arm64/booting.txt in Linux requires that the release address must be zero-initialized, but it is not cared by the common code in U-Boot. We must do it in a board function.
There is no systematic way to protect the spin-table code from the kernel. We are supposed to do it in a board specific manner, but it is difficult to predict where the spin-table code will be located after the relocation. So, it also makes difficult to hard-code /memreserve/ in the DT of the kernel.
So, here is a patch to solve those problems; the DT is run-time modified to reserve the spin-table code (+ cpu-release-addr). Also, the "cpu-release-addr" property is set to an appropriate address after the relocation, which means we no longer need the hard-coded CPU_RELEASE_ADDR.
Signed-off-by: Masahiro Yamada yamada.masahiro@socionext.com
Applied to u-boot/master, thanks!