This patchset reduces the boot time for ARM architecture, Exynos boards, and (ARM) boards with DFU enabled.
For tested Trats2 and Odroid X2 devices, this was done in four steps.
1. Enable the arch memcpy and memset - ARCH specific
2. Enable arch memset for .bss clear - ARCH specific
3. Reduce the .bss section small as possible by: (board specific) - remove static dfu buffer (32MiB in .bss - Trats2), and use malloc
4. Skip zeroing the memory reserved for malloc at malloc init. For Trats2 it was 80MiB of memory.
The .bss section will grow if we have a lot of static variables. This section is cleared before jump to the relocated U-Boot, and it was done word by word. To reduce the time for this step, we can enable arch memset, which uses multiple ARM registers.
For configs with DFU enabled, we can find the dfu buffer in this section, which has at least 8MB (32MB for Trats2). This is a lot of useless data, which is not required for standard boot. So this buffer should be dynamic allocated.
So, actually the all was about unnecessary operations on 'big' data.
Przemyslaw Marczak (6): exynos: config: enable arch memcpy and arch memset arm: relocation: clear .bss section with arch memset if defined dfu: mmc: file buffer: remove static allocation dlmalloc: do memset in malloc init as new default config trats2: defconfig: disable memset at malloc init odroid: defconfig: disable memset at malloc init
Kconfig | 32 +++++++++++++++++++++++++------- arch/arm/lib/crt0.S | 10 +++++++++- common/dlmalloc.c | 10 +++++++--- configs/odroid_defconfig | 1 + configs/trats2_defconfig | 1 + drivers/dfu/dfu_mmc.c | 25 ++++++++++++++++++++++--- include/configs/exynos-common.h | 3 +++ 7 files changed, 68 insertions(+), 14 deletions(-)