The following patches extend accurate time much further back into
the boot process by adding an optional arch_early_time source that
starts counting about 1.75ms after the MMU is enabled.
This exposes currently hidden kernel boot times exceeding 340ms for a 2GByte
dual A9.
Currently only Arm globaltimer is supported as the early time source.
Where the globaltimer is and how to map it is configured by
Device Tree as explained in the second patch.
To get monotonic time in the kernel starting from before the normal time
source can be initialized, the early time source offset is allowed to be
added to scheduler clock time in the first patch.
---
Andy Green (2):
scheduler: time: allow arch-specific time offset function
arm: time: add globaltimer-based arch_early_time
arch/arm/Kconfig | 16 ++++++
arch/arm/Kconfig.debug | 10 ++++
arch/arm/boot/dts/mb8ac0300eb.dts | 10 +++-
arch/arm/configs/fujitsu_defconfig | 2 +
arch/arm/include/asm/memory.h | 8 +++
arch/arm/kernel/devtree.c | 1
arch/arm/kernel/setup.c | 50 ++++++++++++++++++
arch/arm/kernel/time.c | 101 ++++++++++++++++++++++++++++++++++++
arch/arm/mach-mb8ac0300/Kconfig | 3 +
arch/arm/mm/mmu.c | 49 +++++++++++++++++
include/linux/time.h | 7 ++
kernel/sched/clock.c | 12 ++--
mm/Kconfig | 2 -
13 files changed, 263 insertions(+), 8 deletions(-)
--
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