From a9bec67dfda087ac739a29cbc4eb4ccb38da3e45 Mon Sep 17 00:00:00 2001 From: Sandrine Bailleux Date: Fri, 30 Oct 2015 15:05:17 +0000 Subject: Introduce COLD_BOOT_SINGLE_CPU build option This patch introduces a new build option named COLD_BOOT_SINGLE_CPU, which allows platforms that only release a single CPU out of reset to slightly optimise their cold boot code, both in terms of code size and performance. COLD_BOOT_SINGLE_CPU defaults to 0, which assumes that the platform may release several CPUs out of reset. In this case, the cold reset code needs to coordinate all CPUs via the usual primary/secondary CPU distinction. If a platform guarantees that only a single CPU will ever be released out of reset, there is no need to arbitrate execution ; the notion of primary and secondary CPUs itself no longer exists. Such platforms may set COLD_BOOT_SINGLE_CPU to 1 in order to compile out the primary/secondary CPU identification in the cold reset code. All ARM standard platforms can release several CPUs out of reset so they use COLD_BOOT_SINGLE_CPU=0. However, on CSS platforms like Juno, bringing up more than one CPU at reset should only be attempted when booting an EL3 payload, as it is not fully supported in the normal boot flow. For platforms using COLD_BOOT_SINGLE_CPU=1, the following 2 platform APIs become optional: - plat_secondary_cold_boot_setup(); - plat_is_my_cpu_primary(). The Porting Guide has been updated to reflect that. User Guide updated as well. Change-Id: Ic5b474e61b7aec1377d1e0b6925d17dfc376c46b --- bl1/aarch64/bl1_entrypoint.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'bl1') diff --git a/bl1/aarch64/bl1_entrypoint.S b/bl1/aarch64/bl1_entrypoint.S index 4fc52918..83594f21 100644 --- a/bl1/aarch64/bl1_entrypoint.S +++ b/bl1/aarch64/bl1_entrypoint.S @@ -51,7 +51,7 @@ func bl1_entrypoint el3_entrypoint_common \ _set_endian=1 \ _warm_boot_mailbox=!PROGRAMMABLE_RESET_ADDRESS \ - _secondary_cold_boot=1 \ + _secondary_cold_boot=!COLD_BOOT_SINGLE_CPU \ _init_memory=1 \ _init_c_runtime=1 \ _exception_vectors=bl1_exceptions -- cgit v1.2.3