| .. SPDX-License-Identifier: GPL-2.0+ |
| |
| Nokia RX-51 aka N900 |
| ==================== |
| |
| The ``nokia_rx51_defconfig`` configuration file results in a ``u-boot.bin`` |
| which can be chainloaded by the Nokia second stage bootloader (NOLO) in QEMU or |
| on a real N900. It does very little hardware configuration because NOLO has |
| already configured the board. It is only needed to enable the internal eMMC |
| memory via the twl4030 regulator which is not enabled by NOLO. |
| |
| .. code-block:: bash |
| |
| make CROSS_COMPILE=arm-linux-gnueabi- nokia_rx51_defconfig u-boot.bin |
| |
| NOLO is expecting a kernel image and will treat any image it finds in |
| OneNAND as such. This u-boot is intended to be flashed to the N900 like |
| a kernel. In order to transparently boot the original kernel, it will be |
| appended to ``u-boot.bin`` at 0x40000. NOLO will load the entire image into |
| (random) memory and execute U-Boot, which saves hardware revision, boot reason |
| and boot mode ATAGs set by NOLO. Then the bootscripts will attempt to load |
| ``uImage``, ``zImage`` or ``boot.scr`` file from a FAT or ext2/3/4 filesystem |
| on external SD card or internal eMMC memory. If this fails or keyboard is |
| closed then the appended kernel image will be booted using some generated |
| and some stored ATAGs (see boot order). |
| |
| For generating combined image of U-Boot and kernel (either in uImage or zImage |
| format) there is a simple script called ``u-boot-gen-combined``. It is available |
| in following repository: https://github.com/pali/u-boot-maemo. |
| |
| To generate the ``combined.bin`` image from ``u-boot.bin`` and ``kernel.bin`` |
| (in either uImage or zImage format) use: |
| |
| .. code-block:: bash |
| |
| sh u-boot-gen-combined u-boot.bin kernel.bin combined.bin |
| |
| The original Maemo Fremantle PR1.3 zImage kernel binary is available at: |
| http://repository.maemo.org/pool/maemo5.0/free/k/kernel/kernel_2.6.28-20103103+0m5_armel.deb |
| |
| To unpack it (from DEB/AR, TAR and FIASCO) execute the following commands: |
| |
| .. code-block:: bash |
| |
| ar x kernel_2.6.28-20103103+0m5_armel.deb data.tar.gz |
| tar -O -xf data.tar.gz ./boot/zImage-2.6.28-20103103+0m5.fiasco > kernel_2.6.28-20103103+0m5.fiasco |
| 0xFFFF -M kernel_2.6.28-20103103+0m5.fiasco -u |
| |
| The flashed image must start with a 2 KiB ``NOLO!img`` header which contains |
| size of the image. The header consists of the bytes |
| ``NOLO!img\x02\x00\x00\x00\x00\x00\x00\x00`` followed by the 4 byte little |
| endian size of the image. The rest of the 2 KiB header just contains zero bytes. |
| |
| The Nokia proprietary flasher and also the open source 0xFFFF flasher |
| automatically prepend the required ``NOLO!img`` header and both applications |
| expect that the image does not contain a ``NOLO!img`` header. Adding a |
| ``NOLO!img`` header is required only in case of using the ``nandwrite`` tool for |
| flashing. |
| |
| The open source 0xFFFF flasher is available in the following repository: |
| https://github.com/pali/0xFFFF |
| |
| It is possible to load ``u-boot.bin`` via USB to the N900 RAM and boot it |
| without needing to flash it. This is done via 0xFFFF running on the host PC: |
| |
| .. code-block:: bash |
| |
| 0xFFFF -m u-boot.bin -l -b |
| |
| 0xFFFF also supports flashing a kernel image either via USB or directly on |
| N900 device. Flashing u-boot/kernel/combined image is done as: |
| |
| .. code-block:: bash |
| |
| 0xFFFF -m combined.bin -f |
| |
| Via 0xFFFF it is also possible to generate a standard flashable image in |
| Nokia FIASCO format which contains metadata information like device |
| identification (RX-51) and version string (v2021.04): |
| |
| .. code-block:: bash |
| |
| 0xFFFF -m RX-51:v2021.04:kernel:u-boot.bin -g u-boot.fiasco |
| |
| There is support for the hardware watchdog. The hardware watchdog is started by |
| NOLO so U-Boot must reset the watchdog to prevent rebooting the device (but not |
| very often, max every 2 seconds). There is also support for framebuffer display |
| output with ANSI escape codes and the N900 hardware keyboard input. |
| |
| When U-Boot is starting it sets the IBE bit in the Auxiliary Control Register, |
| which is needed for Thumb-2 ISA support. This is a workaround for erratum |
| 430973. |
| |
| Default boot order |
| ------------------ |
| |
| 0. if keyboard is closed boot automatically attached kernel image |
| 1. try boot from external SD card |
| 2. try boot from internal eMMC memory |
| 3. try boot from attached kernel image |
| |
| Boot from SD or eMMC in this order: |
| |
| 1. boot from FAT partition |
| |
| a. find ``boot.scr`` on first FAT partition |
| b. find ``uImage`` on first FAT partition |
| c. find ``zImage`` on first FAT partition |
| d. same order for 2nd - 4th FAT partition |
| |
| 2. same as 1. but for ext2/3/4 partition |
| |
| Available additional commands/variables |
| --------------------------------------- |
| |
| * run sdboot - Boot from external SD card (see boot order) |
| * run emmcboot - Boot from internal eMMC memory (see boot order) |
| * run attachboot - Boot attached kernel image (attached to U-Boot binary) |
| |
| \ |
| |
| * run scriptload - Load boot script ``${mmcscriptfile}`` |
| * run scriptboot - Run loaded boot script |
| * run kernload - Load kernel image ``${mmckernfile}`` |
| * run initrdload - Load initrd image ``${mmcinitrdfile}`` |
| * run kernboot - Boot loaded kernel image |
| * run kerninitrdboot - Boot loaded kernel image with loaded initrd image |
| |
| \ |
| |
| * run trymmcscriptboot - Try to load and boot script ``${mmcscriptfile}`` |
| * run trymmckernboot - Try to load and boot kernel image ``${mmckernfile}`` |
| * run trymmckerninitrdboot - Try to load and boot kernel image ``${mmckernfile}`` |
| with initrd image ``${mmcinitrdfile}`` |
| |
| Additional variables for loading files from mmc |
| ----------------------------------------------- |
| |
| * mmc ``${mmcnum}`` (0 - external, 1 - internal) |
| * partition number ``${mmcpart}`` (1 - 4) |
| * partition type ``${mmctype}`` (fat, ext2, ext4; ext2 is just alias for ext4) |
| |
| Additional variables for booting a kernel |
| ----------------------------------------- |
| |
| * ``setup_omap_atag`` - Add OMAP table into atags structure (needed for maemo kernel) |
| * ``setup_console_atag`` - Enable serial console in OMAP table |
| * ``setup_boot_reason_atag`` - Change boot reason in OMAP table |
| * ``setup_boot_mode_atag`` - Change boot mode in OMAP table |
| |
| Variable ``setup_omap_atag`` is automatically set when booting attached kernel. |
| When variable ``setup_omap_atag`` is set, variable ``setup_console_atag`` is unset |
| and u-boot standard output is set to serial then ``setup_console_atag`` is |
| automatically set to 1. So output from Maemo kernel would go to serial port. |
| |
| UBIFS support |
| ------------- |
| |
| UBIFS support is disabled, because U-Boot image is too big and cannot be |
| flashed with attached kernel image to RX-51 kernel nand area. For enabling |
| UBIFS support add following lines into file ``configs/nokia_rx51_defconfig``:: |
| |
| CONFIG_CMD_UBI=y |
| CONFIG_CMD_UBIFS=y |
| CONFIG_MTD_UBI_BEB_LIMIT=10 |
| |
| Early output |
| ------------ |
| |
| Early U-Boot output can be enabled on serial console by adding following lines |
| into file ``configs/nokia_rx51_defconfig``:: |
| |
| CONFIG_DEBUG_UART=y |
| CONFIG_DEBUG_UART_OMAP=y |
| CONFIG_DEBUG_UART_SHIFT=2 |
| CONFIG_DEBUG_UART_BASE=0x49020000 |
| CONFIG_DEBUG_UART_CLOCK=48000000 |
| |
| Note that early output is not available on USB tty console. |
| |
| Verbose debug output |
| -------------------- |
| |
| Verbose debug output with maximal log level can be enabled by adding following |
| lines into file ``configs/nokia_rx51_defconfig``:: |
| |
| CONFIG_DM_DEBUG=y |
| CONFIG_LOG=y |
| CONFIG_LOGLEVEL=9 |
| CONFIG_LOG_MAX_LEVEL=9 |
| CONFIG_LOG_DEFAULT_LEVEL=9 |
| |
| And compiling U-Boot by additional make parameter ``KCPPFLAGS=-DLOG_DEBUG``. |
| |
| Run in QEMU |
| ----------- |
| |
| Download and compile Linaro version of qemu which contains ``n900`` qemu |
| machine. Source code is available in qemu-linaro git repository and the |
| last working version is at commit 8f8d8e0796efe1a6f34cdd83fb798f3c41217ec1. |
| |
| Use following commands to compile ``qemu-system-arm`` binary with ``n900`` |
| qemu machine support: |
| |
| .. code-block:: bash |
| |
| git clone https://git.linaro.org/qemu/qemu-linaro.git |
| cd qemu-linaro |
| git checkout 8f8d8e0796efe1a6f34cdd83fb798f3c41217ec1 |
| ./configure --enable-system --target-list=arm-softmmu --disable-werror |
| make -j4 |
| cd .. |
| ln -s qemu-linaro/arm-softmmu/qemu-system-arm . |
| |
| Using ``n900`` qemu machine requires proprietary Nokia qemu ``qflasher`` tool |
| (in reality it is just generator of qemu MTD images) with first stage images |
| (``xloader-qemu.bin`` and ``secondary-qemu.bin``), similar what is required |
| on the real HW. License of flasher and images allows non-commercial |
| redistribution and it is available at maemo.org website: |
| |
| .. code-block:: bash |
| |
| wget -c http://repository.maemo.org/qemu-n900/qemu-n900.tar.gz |
| tar -xf qemu-n900.tar.gz |
| |
| To generate qemu bootable MTD image ``mtd.img`` from U-Boot binary |
| ``u-boot.bin`` and unpacked first stage images, run following command: |
| |
| .. code-block:: bash |
| |
| ./qflasher -v -x xloader-qemu.bin -s secondary-qemu.bin -k u-boot.bin -m rx51 -o mtd.img |
| |
| Instead of ``u-boot.bin`` binary it is possible to also used combined |
| U-Boot + kernel binary ``combined.bin``. |
| |
| Finally, to boot ``mtd.img`` with graphics display and keyboard with optional |
| serial console on current terminal, run: |
| |
| .. code-block:: bash |
| |
| ./qemu-system-arm -M n900 -mtdblock mtd.img -serial /dev/tty |
| |
| Additionally it is possible to emulate also eMMC and uSD card by appending |
| qemu ``-sd`` arguments: |
| |
| .. code-block:: bash |
| |
| ./qemu-system-arm -M n900 -mtdblock mtd.img -sd emmc.img -sd sd.img -serial /dev/tty |
| |
| For more examples, look into the ``test/nokia_rx51_test.sh`` CI testing script. |