U-Boot
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QT2410 # ext2load mmc 0 0x32000000 rootfs.jffs2 | QT2410 # ext2load mmc 0 0x32000000 rootfs.jffs2 | ||
− | QT2410 # nand erase | + | QT2410 # nand erase rootfs |
− | QT2410 # nand write.e 0x32000000 | + | QT2410 # nand write.e 0x32000000 rootfs real_size_of_rootfs_in_hex |
</pre> | </pre> | ||
Revision as of 01:50, 10 February 2007
Contents |
General
The GTA01 uses the u-boot bootloader.
More information on u-boot can be found at [1], [2] and [3].
However, the vanilla u-boot doesn't support many of the features that GTA01 needs, such as
- Support for boot from NAND flahs using S3C2410 Steppingstone
- Support for reading kernel/initrd from SD/Transflash
- Support for S3C2410 NAND flash
- Support for downloading programs via S3C2410 USB Device Controller
- Support to display bootup logo / status on S3C2410 Framebuffer
User:HaraldWelte is working on those issues, and in fact most of them have already been implemented.
Bootloader source code
The current bootloader patches can be found at https://svn.openmoko.org/trunk/src/target/u-boot/patches/.
Untar the sources, apply the patch. run "make gta01bv3_config" (or gta01bv2_config, or whatever hardware revision you have), run "make". You will get a resulting "u-boot.bin" image, which you can directly flash (either using existing bootloader or sjf2410-linux) into NAND.
Bootloader binary
The latest bootloader binary (for NAND) can be found at [4]. It should be written to the NAND flash address 0x00000000 (size 0x30000)
Bootloader development
QT2410
If you want to do bootloader development on the QT2410, it's easier to work with a bootloader image that can be downloaded via USB into RAM instead of flashing.
To do so, you need to edit the u-boot/include/configs/qt2410.h file, and change the "if 0" in Line 32 into a "if 1", then recompile with "make".
The resulting "u-boot.bin" is _NOT SUITABLE_ for NAND flash, but only for direct execution from within ram, e.g. by using the s3c2410_boot_usb program.
GTA01
Doing bootloader development on the GTA01 is a bit more tricky. first, we don't have any NOR flash. Second, there is no other way to boot _but_ from NAND. Therefore, we also don't have a USB downloader like the QT2410.
The main problem is: The S3C2410 Steppingstone unconditionally copies the first 4k of flash into its internal SRAM. That SRAM segment stays unconditionally mapped at physical address zero. How do we get around this
Using JTAG to boot from RAM
So how can we boot from RAM? We use JTAG / OpenOCD to
- reset and halt the cpu at PC=0
> reset halt target halted in ARM state due to debug request, current mode: Supervisor cpsr: 0x400000d3 pc: 0x00000000 MMU: disabled, D-Cache: disabled, I-Cache: disabled
- download a small piece of code for low-level SDRAM timing initialization (overwrite 4k SRAM of steppingstone)
> load_binary /space/misc/gta01/u-boot.git/foo.bin 0 downloaded 332 byte in 0s 21899us
- assert a break point at address 0x33f80000 (which indicates that the low-level code has finished)
> bp 0x33f80000 4 hw breakpoint added at address 0x33f80000
- run the code up to the break point
> resume Target 0 resumed > Target 0 halted target halted in ARM state due to breakpoint, current mode: Supervisor cpsr: 0x600000d3 pc: 0x33f80000 MMU: disabled, D-Cache: disabled, I-Cache: enabled
- download the u-boot RAM image to 0x33f80000
> load_binary /space/misc/gta01/u-boot.git/u-boot.bin 0x33f80000 downloaded 135692 byte in 6s 567264us
- resume processing
> resume Target 0 resumed
At this point, the display backlight gets bright and we see the following familiar prompt on the serial console:
U-Boot 1.1.6 (Jan 13 2007 - 23:44:23) DRAM: 128 MB NAND: 64 MiB *** Warning - bad CRC or NAND, using default environment In: serial Out: serial Err: serial Hit any key to stop autoboot: 0 GTA01Bv2 #
Creating bootable images
u-boot needs bootable images (such as kernels, but also initrd and others) in form of a so-called uImage. In order to create a uImage from e.g. a vmlinux kernel image, you can proceed as follows:
objcopy -O binary -R .note -R .comment -S vmlinux linux.bin gzip -9 linux.bin u-boot/tools/mkimage -A arm -O linux -T kernel -C gzip -a 30008000 -e 30008000 -n "Kernel Image QT2410" -d linux.bin.gz uImage
Bootloader prompt
The bootloader prompt is available either on the serial console (via Debug Board), or as virtual USB Serial device (USB CDC_ACM). Whether the serial port or usb i used depends on the u-boot environment variables stdin, stdout and stderr.
Whether or not you use usbtty, the first couple of messages will always be displayed on the serial console.
The bootloader is currently configured to waid for three seconds. If a key press on the serial port is received within those three seconds, auto-boot is aborted.
U-Boot 1.1.4-ga2c95a72-dirty (Aug 6 2006 - 22:05:48) DRAM: 64 MB Flash: 512 kB NAND: 64 MiB In: serial Out: serial Err: serial cs8900a chipid 0x630e Hit any key to stop autoboot: 0 QT2410 #
Auto-boot
Auto-boot executes the command[s] specified in the bootcmd environment variable. The default configuration is:
GTA01Bv2 # printenv bootcmd=nand read.e 0x32000000 kernel; bootm 0x32000000
This basically tells us that it will load the content of the NAND partition kernel to memory address 0x32000000 and then try to boot it.
Environment
u-boot is configured to manage a non-volatile environment that is stored in NAND flash. You can use the commands to read/alter/store the environment in the following example:
QT2410 # printenv bootcmd=mmcinit; ext2load mmc 0 0x32000000 uImage; bootm 0x32000000 bootdelay=3 baudrate=115200 ipaddr=10.0.0.110 serverip=10.0.0.1 netmask=255.255.255.0 bootargs=root=/dev/mmcblk0p1 console=ttySAC0,115200 loglevel=8 rootdelay=10 stdin=serial stdout=serial stderr=serial Environment size: 271/16380 bytes QT2410 # setenv bootdelay 10 QT2410 # printenv bootdelay bootdelay=10 QT2410 # saveenv Saving Environment to NAND... Erasing Nand...Writing to Nand... done QT2410 #
Note: When setting multiple commands, e.g. for bootcmd, you need to escape the ';', for instance
QT2410 # setenv bootcmd mmcinit\; ext2load mmc 0 0x32000000 uImage\; bootm 0x32000000
As of 2007-02-01, laforge says the correct bootargs are:
rootfstype=jffs2 root=/dev/mtdblock4 console=ttySAC0,115200 console=tty0 loglevel=8
Note that this requires flashing the jffs2 root image into NAND.
MMC/SD
in order to initialize a MMC/SD card, you have to use the ``mmcinit command.
QT2410 # mmcinit trying to detect SD Card... MMC found. Card desciption is: Manufacturer ID = 58d564 HW/FW Revision = 3 8 Product Name = 21DN!@X� Serial Number = 445303 Month = 5 Year = 2000 READ_BL_LEN=15, C_SIZE_MULT=7, C_SIZE=3197 size = 4208984064
afterwards, you can read ext2 filesystems like:
QT2410 # ext2ls mmc 0 <DIR> 1024 . <DIR> 1024 .. <DIR> 12288 lost+found 1544788 uImage
NAND
QT2410 # help nand nand info - show available NAND devices nand device [dev] - show or set current device nand read[.jffs2] - addr off size nand write[.jffs2] - addr off size - read/write `size' bytes starting at offset `off' to/from memory address `addr' nand erase [clean] [off size] - erase `size' bytes from offset `off' (entire device if not specified) nand bad - show bad blocks nand dump[.oob] off - dump page nand scrub - really clean NAND erasing bad blocks (UNSAFE) nand markbad off - mark bad block at offset (UNSAFE) nand biterr off - make a bit error at offset (UNSAFE)
Loading Kernel from NAND
QT2410 # nand read 0x32000000 0x34000 0x200000 NAND read: device 0 offset 212992, size 2097152 ... 2097152 bytes read: OK QT2410 # bootm 0x32000000 ## Booting image at 32000000 ... Image Name: Kernel Image QT2410 Created: 2006-08-06 20:23:01 UTC Image Type: ARM Linux Kernel Image (gzip compressed) Data Size: 1546258 Bytes = 1.5 MB Load Address: 30008000 Entry Point: 30008000 Verifying Checksum ... OK Uncompressing Kernel Image ... OK Starting kernel ...
Writing new bootloader to NAND
The following set of commands loads the file u-boot.bin from ext2/mmc and flashes it into the bootloader flash partition:
QT2410 # ext2load mmc 0 0x32000000 u-boot.bin QT2410 # nand erase u-boot QT2410 # nand write 0x32000000 u-boot
Writing kernel to NAND
The following set of commands loads the file uImage from ext2/mmc and flashes it into the kernel flash partition:
QT2410 # ext2load mmc 0 0x32000000 uImage QT2410 # nand erase kernel QT2410 # nand write.e 0x32000000 kernel
Writing rootfs to NAND
The following set of commands loads the file rootfs.jffs2 from ext2/mmc and flashes it into the rootfs flash partition:
QT2410 # ext2load mmc 0 0x32000000 rootfs.jffs2 QT2410 # nand erase rootfs QT2410 # nand write.e 0x32000000 rootfs real_size_of_rootfs_in_hex
Please note that this will only work with root file system sizes that are smaller than the amount of memory above 0x32000000, which in the case of 64MB SDRAM is something like 32MB.
TFTP on QT2410
The QT2410 cs8900a Ethernet can be used to download images via network.
First, you have to make sure that ipaddr, serverip, ethaddr' and netmaskk are set correctly in the environment:
QT2410 # printenv ethaddr=00:01:02:03:04:05 netmask=255.255.255.0 ipaddr=192.168.100.100 serverip=192.168.100.1
TFTP kernel download
QT2410 # tftpboot 0x32000000 *** Warning: no boot file name; using 'C0A86464.img' TFTP from server 192.168.100.1; our IP address is 192.168.100.100 Filename 'C0A86464.img'. Load address: 0x32000000 Loading: ################################################################# ################################################################# ################################################################# ################################################################# ########################################## done Bytes transferred = 1544788 (179254 hex)
you can then commence booting via
QT2410# bootm 0x32000000