VMC Volatile memory controller

RE: VMC Volatile memory controller

Kenneth — Tue, 01 Feb 2022 13:54:55 GMT

Thanks for sharing!

RE: VMC Volatile memory controller

artop — Tue, 01 Feb 2022 13:41:00 GMT

Finally got this working. Required rather extensive study of how things are built and linked. I was hoping to be able to patch bootloader without touching SDK directories, but did not find a way. If there is nicer way to achieve the same suggestions are welcome.

Mcuboot Modifications

At ncs/v1.7.0/bootloader/mcuboot

To the end of CMakeLists.txt:

zephyr_library_sources(
 ${CMAKE_CURRENT_SOURCE_DIR}/boot_keep_out.c
)
zephyr_linker_sources(SECTIONS boot_keep_out.ld)

New file boot_keep_out.c:

#include <stdint.h>

/* Reserve one memory section for retainable ram across boots */
#define BOOT_LOADER_KEEP_OUT_REGION_SIZE 0x3000
__attribute__((section(".boot_loader_keep_out")))
uint8_t boot_loader_keep_out_ram[BOOT_LOADER_KEEP_OUT_REGION_SIZE];

New file boot_keep_out.ld:

SECTION_PROLOGUE (boot_loader_keep_out, 0x2006A000 (NOLOAD),)
{
 KEEP(*(SORT_BY_NAME(".boot_loader_keep_out*")))
}

Application Modifications

To app CMakeLists.txt:

set(PM_STATIC_YML_FILE "${CMAKE_CURRENT_SOURCE_DIR}/pm_static.yml")
zephyr_linker_sources(SECTIONS src/boot_keep_out.ld)

To pm_static.yml file:

# Reserve area from RAM to be retained by boot through modified mcuboot
sram_primary:
 address: 0x20000000
 end_address: 0x2006a000
 region: sram_primary
 size: 0x6a000

retained_sram:
 address: 0x2006a000
 end_address: 0x2006e000
 placement:
 before:
 - pcd_sram
 after:
 - sram_primary
 region: retained_sram
 size: 0x3000

C file with retained data:

__in_section_unique(boot_loader_keep_out) struct retained_data retained;

src/boot_keep_out.ld

SECTION_PROLOGUE (boot_loader_keep_out, 0x2006A000 (NOLOAD),)
{
 KEEP(*(SORT_BY_NAME(".boot_loader_keep_out*")))
}

Block Calculation Hints

#define SRAM_BEGIN (uintptr_t)DT_REG_ADDR(DT_NODELABEL(sram0))
#define SRAM_END (SRAM_BEGIN + (uintptr_t)DT_REG_SIZE(DT_NODELABEL(sram0)))
/* Number of blocks */
#define BLOCK_COUNT 8
/* Sections / block */
#define SECTIONS_PER_BLOCK 16
/* Size of a controllable RAM section in the small blocks */
#define SECTION_SIZE 4096

NRF_VMC_S->RAM[block].POWERSET = 1LU << (VMC_RAM_POWER_S0RETENTION_Pos + section);
volatile uint32_t dummy = NRF_VMC_S->RAM[block].POWERSET;
ARG_UNUSED(dummy);

- Arto

RE: VMC Volatile memory controller

Kenneth — Thu, 27 Jan 2022 09:24:14 GMT

I could find these threads:

https://github.com/zephyrproject-rtos/zephyr/issues/31087

https://github.com/mcu-tools/mcuboot/issues/905

In specific check out: https://github.com/mcu-tools/mcuboot/issues/905#issuecomment-768551026

Kenneth

RE: VMC Volatile memory controller

artop — Wed, 26 Jan 2022 09:02:00 GMT

Hi,

Thanks for pointing to correct pages, hal/nrf_vmc.h header seems to be incorrect then. It would also be good to update link at WMC documentation to point at more informative pages.

Actual retaining has some issue though. Even reset (kernel reboot warm) seems to fill noinit section with 0xFF. And when right retain bit is set I'm not able to get similar CRC check that system off example uses to pass.

Can for example debugging affect this?

- Arto

RE: VMC Volatile memory controller

Kenneth — Tue, 25 Jan 2022 13:43:59 GMT

Hi,

Maybe you are looking for these figures:
https://infocenter.nordicsemi.com/topic/ps_nrf5340/chapters/memory/appmem.html
https://infocenter.nordicsemi.com/topic/ps_nrf5340/chapters/memory.network/netmem.html

Kenneth