The goal of the document is to illustrate how to create an SD card with SP7021 Linux kernel and root file-system. Please follow the following steps.
1. Run ‘make config’
Get latest code from git server of SP7021 (2. HOW TO GET SOURCE FILE AND PACKAGE ) and run make config command on top folder. After configuration menu pops up, first, choose board you want to build image for. For example, press 3 for SP7021 Demo Board (V3). Second, press 1 for selecting C-chip. Finally, press 4 and then enter to start to configure building environment. Refer to screenshot below,
‘make config’ is starting to configure building environment. It takes 1~2 minutes to complete.
2. Run ‘make all’
Run make all command to start to create image for SD card. It might take several minutes to complete. After 'make all' completes, you will see screen like:
From information on screen, two partitions are created in the image of SD card. The first partition starts at sector 2048 and ends at sector 104447. Its size is 50 MiB and file-system is W95 FAT. The second partition starts at sector 104448 and ends at sector 137215. Its size is 16 MiB and file-system is Linux (ext3).
3. Image files
The built image files are stored at out/boot2linux_SDcard/. Refer to screenshot of list of the folder:
ISPBOOOT.BIN is a binary file in which xboot is stored. xboot is a boot-loader which loads and runs u-boot during power-on booting processes. u-boot.img is u-boot image file. u-boot is the second stage boot-loader. It loads and runs Linux kernel image. uImage is an image file of compressed Linux kernel with u-boot header. uEnv.txt is an environment file of u-boot. u-boot imports environment variables in the file after it completes initializing. If uenvcmd command is defined in uEnv.txt, u-boot runs the uenvcmd command after it completes importing uEnv.txt. a926.img is an image file for processor A926. A926 processor is designed for taking care of real-time tasks. The default script of u-boot will load and run a926.img it if it exists in root of boot partition.
ISP_SD_BOOOT.img is an image for burning an SD card. It actually contains all files in both partitions.
4. Write image to an SD card
Use an application to write image file, ISP_SD_BOOOT.img, to an SD card. The capacity of SD card should be larger than size of image file, ISP_SD_BOOOT.img. For example, if you want to use “Win32 Disk Imager” to write image to an SD card. First, download the it from https://sourceforge.net/projects/win32diskimager/:
Then, install and run it. After application window pops, select “Image File” and “Device”. Finally, press “Write” button to start to write. Refer to screenshot when “Win32 Disk Imager” is writing image file, ISP_SD_BOOOT.img, to an SD card (F:\) below:
Another example is using “balenaEtcher”. Refer to screenshot when “balenaEtcher” is writing image file, ISP_SD_BOOOT.img, to an SD card below:
5. Boot from an SD card
Insert your SD card to SP7021 board and set its DIP-SW to for booting from SD card. For example, if you are using SP7021 Demo Board (V1/V2/V3), you need to set DIP-SW to ON-ON for booting from SD card. Refer to picture below:
DIP-SW is set to ON-ON.
Turn on power of SP7021 board to start booting.
6. Extend size of root file-system
At the first time, Linux boots from a new SD card. The built-in script of Linux will run fdisk command to extend the size of rootfs partition to the end of SD card and then re-boot. Refer to log while Linux script is extending size of rootfs partition:
| Code Block |
|---|
[ 2.002577] devtmpfs: mounted
[ 2.004625] Freeing unused kernel memory: 1024K
[ 2.004826] Run /sbin/init as init process
/etc/init.d/rcS starts...
Mounting other filesystems ...
rc.extra [bg]
sdcard boot set...
partition set
0x00001746
totalsize=16358834176
0x0000000A
extra done
totalsize=31950840 startsector=104448
The number of cylinders for this disk is set to 499232.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
(e.g., DOS FDISK, OS/2 FDISK)
Command (m for help): Disk /dev/mmcblk1: 15 GB, 16358834176 bytes, 31950848 sectors
499232 cylinders, 4 heads, 16 sectors/track
Units: sectors of 1 * 512 = 512 bytes
Device Boot StartCHS EndCHS StartLBA EndLBA Sectors Size Id Type
/dev/mmcblk1p1 0,32,33 6,127,57 2048 104447 102400 50.0M b Win95 FAT32
/dev/mmcblk1p2 6,127,58 8,138,2 104448 137215 32768 16.0M 83 Linux
Command (m for help): Partition number (1-4):
Command (m for help): Partition type
p primary partition (1-4)
e extended
Partition number (1-4): First sector (16-31950847, default 16): Last sector or +size{,K,M,G,T} (104448-31950847, default 31950847):
Command (m for help): Disk /dev/mmcblk1: 15 GB, 16358834176 bytes, 31950848 sectors
499232 cylinders, 4 heads, 16 sectors/track
Units: sectors of 1 * 512 = 512 bytes
Device Boot StartCHS EndCHS StartLBA EndLBA Sectors Size Id Type
/dev/mmcblk1p1 0,32,33 6,127,57 2048 104447 102400 50.0M b Win95 FAT32
/dev/mmcblk1p2 1023,3,16 1023,3,16 104448 31950840 31846393 15.1G 83 Linux
Command (m for help): The partition table has been altered.
Calling ioctl() to re-read partition table
fdisk: WARNING: rereading partition table failed, kernel still uses old table: Device or resource busy
End of /etc/init.d/rcS
[ 4.319145] EXT4-fs (mmcblk1p2): re-mounted. Opts: (null)
The system is going down NOW!
Sent SIGTERM to all processes
Sent SIGKILL to all processes
Requesting system reboot |
The latest command in the script is reboot command. You’ll see system re-boot after script completes extending size of rootfs partition.
After system re-boots successfully, built-in script of Linux will run resize2fs to resize the root file-system to make use of the whole partition (It was extended in previous step.). It takes a while for completing resizing rootfs. Refer to screenshot when resizing:
Resizing has completed. You are ready to use SP7021 Linux.
Appendix: How to extend size of rootfs partition to maximum manually?
1. Use fdisk to extend size of rootfs partition to end of the SD card.
Run fdisk as below:
fdisk /dev/mmcblk1
where SD card device is at /dev/mmcblk1.
a) Press p to list partitions of the SD card.
b) Press d and then 2 to delete the second (rootfs) partition.
c) Press p to list partitions of the SD card again.
d) Press n and, p, 2, 104448 and then 31950839 to add back the second (rootfs) partition. Note that 104448 is start-LBA while 31950839 is new end-LBA of the partition.
e) Press p to list partitions of the SD card again. Confirm modification of partitions.
f) Press w to write back partition to the SD card.
g) Run reboot command to re-boot system.
Refer to screenshot below:
2. Run resize2fs to extend size of file-system to make use the whole partition
Run resize2fs command as below:
resize2fs /dev/mmcblk1p2