Hi Jacob,
On Fri, Dec 30, 2016 at 03:28:08PM -0700, Jacob Rosenthal wrote:
> I think deps are a part of the story, but yeah the goal is to successfully
> get a target bsp back to 1 larger flash image, or as many as the common set
> of deps require but shrunk way down.
So you just want to eliminate the need for a second image slot in the
flash map?
There are four flash areas that are relevant here. Just to be clear: a
flash area is simply a named region of flash. Each BSP's bsp.yml file
defines its flash map as a sequence of flash areas.
Anyway, the four relevant flash areas are:
* FLASH_AREA_BOOTLOADER:
* FLASH_AREA_IMAGE_0:
* FLASH_AREA_IMAGE_1:
* FLASH_AREA_IMAGE_SCRATCH:
The boot loader area is placed at the board's start address in flash.
That is, the device boots directly into the boot loader. The boot
loader then possibly swaps the two image slots and jumps to the image in
slot 0. This process is described in some detail in
boot/bootutil/design.txt.
If your device only needs a single image, you have two options:
1. slot-1 stub
2. no boot loader
Option 1 is the simplest, but option 2 gives you more flash space. I
will describe both options below.
*** Slot-1 stub:
This option involves greatly reducing the size of the FLASH_AREA_IMAGE_1
area. When I did this with the nRF51dk, I used an area size of 2kB. I
think you shld be able to reduce it to the size of an individual
sector (1kB), but I have not tried this.
There are two changes you need to make:
* (bsp.yml)
o Increase the size of FLASH_AREA_IMAGE_0.
o Reduce the size of FLASH_AREA_IMAGE_1.
o Increase the offset of FLASH_AREA_IMAGE_0.
* (nrf51xxac.ld)
o Increase the size of the FLASH region.
I have attached modified versions of these two files that you can try.
*** No boot loader:
This option involves removing the boot loader entirely.
Instead of a boot loader, the image binary is placed at the board's
start address in flash such that the device boots directly into it.
Without a boot loader, you can eliminate the following two areas from
the flash map:
* FLASH_AREA_BOOTLOADER:
* FLASH_AREA_IMAGE_1:
Unfortunately, the scratch area cannot be eliminated at the moment,
since it is required by the reboot log. I think this is something we
should address soon, but in the meantime, you are stuck with the scratch
area.
It has been a while since I've tried running an image without a boot
loader, so my memory might be a bit foggy. I think the following steps
are all you need:
* (bsp.yml)
o Remove FLASH_AREA_BOOTLOADER
o Remove FLASH_AREA_IMAGE_1
o Increase the size of FLASH_AREA_IMAGE_0.
o Reduce the offset of FLASH_AREA_IMAGE_0.
* (nrf51xxac.ld)
o Increase the size of the FLASH region.
o Set _imghdr_size to 0.
You will probably also need to move the reboot log flash area.
Currently, most BSPs place it right between the boot loader and image
slot 0.
Let me know if you have any questions.
Thanks,
Chris
#
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements. See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.
#
bsp.arch: cortex_m0
bsp.compiler: compiler/arm-none-eabi-m0
bsp.linkerscript:
- "hw/bsp/nrf51dk/nrf51xxac.ld"
- "hw/mcu/nordic/nrf51xxx/nrf51.ld"
bsp.linkerscript.BOOT_LOADER.OVERWRITE:
- "hw/bsp/nrf51dk/boot-nrf51xxac.ld"
- "hw/mcu/nordic/nrf51xxx/nrf51.ld"
bsp.part2linkerscript: "hw/bsp/nrf51dk/split-nrf51dk.ld"
bsp.downloadscript: "hw/bsp/nrf51dk/nrf51dk_download.sh"
bsp.debugscript: "hw/bsp/nrf51dk/nrf51dk_debug.sh"
bsp.flash_map:
areas:
# System areas.
FLASH_AREA_BOOTLOADER:
device: 0
offset: 0x00000000
size: 16kB
FLASH_AREA_IMAGE_0:
device: 0
offset: 0x00008000
size: 218kB
FLASH_AREA_IMAGE_1:
device: 0
offset: 0x0003e800
size: 2kB
FLASH_AREA_IMAGE_SCRATCH:
device: 0
offset: 0x0003f000
size: 2kB
# User areas.
FLASH_AREA_REBOOT_LOG:
user_id: 0
device: 0
offset: 0x00004000
size: 16kB
FLASH_AREA_NFFS:
user_id: 1
device: 0
offset: 0x0003f800
size: 2kB
/* Linker script for Nordic Semiconductor nRF5 devices
*
* Version: Sourcery G++ 4.5-1
* Support: https://support.codesourcery.com/GNUToolchain/
*
* Copyright (c) 2007, 2008, 2009, 2010 CodeSourcery, Inc.
*
* The authors hereby grant permission to use, copy, modify, distribute,
* and license this software and its documentation for any purpose, provided
* that existing copyright notices are retained in all copies and that this
* notice is included verbatim in any distributions. No written agreement,
* license, or royalty fee is required for any of the authorized uses.
* Modifications to this software may be copyrighted by their authors
* and need not follow the licensing terms described here, provided that
* the new terms are clearly indicated on the first page of each file where
* they apply.
*/
MEMORY
{
FLASH (rx) : ORIGIN = 0x00008000, LENGTH = 0x36800
RAM (rwx) : ORIGIN = 0x20000000, LENGTH = 0x8000
}
/* This linker script is used for images and thus contains an image header */
_imghdr_size = 0x20;
