I am compiling my own kernel and bootloader (U-boot). I added a bunch of new environmental variables, but U-boot doesn't load anymore (it just doesn't load anything from the memory). I am using pocketbeagle and booting from an SD card. Thus I am editing the file "am335x_evm.h" found in /include/configs/.
I am trying to allocate U-boot in a way that it has more space for the environmental variables and that it can load succesfully from the memory, but I have been unable to do so. As far as I understand, by default it allocates 128kb of memory to U-boot env variables. Since I added a bunch of them, I am trying to increase its size from 128kb to 512kb.
I have changed the following line (from 128kb to 512kb):
#define CONFIG_ENV_SIZE (512 << 10)
(By the way, anyone knows why it is shifted to the left 10 bits?)
I have also changed CONFIG_ENV_OFFSET and CONFIG_ENV_OFFSET_REDUND to:
#define CONFIG_ENV_OFFSET (1152 << 10) /* Originally 768 KiB in */
#define CONFIG_ENV_OFFSET_REDUND (1664 << 10) /* Originally 896 KiB in */
Then after compiling the new U-boot, I format the SD card and insert the new kernel and U-boot.
I start by erasing partitions:
export DISK=/dev/mmcblk0
sudo dd if=/dev/zero of=${DISK} bs=1M count=10
Then I transfer U-boot by doing:
sudo dd if=./u-boot/MLO of=${DISK} count=1 seek=1 bs=512k
sudo dd if=./u-boot/u-boot.img of=${DISK} count=2 seek=1 bs=576k
I then create the partition layout by doing:
sudo sfdisk ${DISK} <<-__EOF__
4M,,L,*
__EOF__
Then I add the kernel, binary trees, kernel modules, etc... When trying to boot and reading the serial port, I get nothing at all. U-boot is not able to load anything from the SD card. What am I doing wrong? I'd appreciate if you could point me what my problem is and exactly what I should be doing to increase the size and allocate everything correctly.
Related
I'd like to back up a SSD which I'm using for CentOS. Trying to learn dd. My drive is a fairly simple GPT partition of 120GB.
I run "dd" to copy the image of sda to a USB stick sdd1:
[root#localhost ~]# dd if=/dev/sda conv=sync,noerror status=progress bs=64k of=/dev/sdd1
120029118464 bytes (120 GB, 112 GiB) copied, 30810 s, 3.9 MB/s
1831575+1 records in
1831576+0 records out
120034164736 bytes (120 GB, 112 GiB) copied, 30810.8 s, 3.9 MB/s
But then when I examine the USB stick, there is nothing to be seen on it and I see no way to mount it
this is what appears under the Disks command
Question is:
How do I access the image?
(As a side note, I read a claim that the dd command is like the IBM JCL statement of the same name. I was a mainframe programmer. The IBM DD command is often still called a "DD Card". It doesn't copy files. It just joins your file declaration in your program to some external file. To copy a file the old skool way is to use IEBGENER)
if=/dev/sda Is cloning the entire disk and of=/dev/sdd1 Is writing to a partition. Which doesn't make much sense.
You may want to clone the entire disk onto another disk
dd if=/dev/sda conv=sync,noerror status=progress bs=64k of=/dev/sdd
Or better yet clone to an compressed image
dd if=/dev/sda | gzip > /sda.img.gz
And restore like so
gzip -d /sda.img.gz | dd of=/dev/sda
I know we can use NFS, but I just don't want to use it.
(don't want to keep network connection to NFS server all the time).
I know we can use tftp in u-boot to load kernel and device-tree!
But can we use tftp in u-boot to download root-filesystem, put it in the right partition of SD card, and boot?
If yes, how to do it? (I googled, but found no answers)
Thanks,
Jerry
I use TFTP in uboot to flash my rootfs (for debug purposes) on my internal eMMC. It's nearly the same case as you.
First download in you RAM the filesystem:
tftpboot ${rootfs_addr} ${tftppath}/${rootfs_file}
rootfs_addr will be the RAM address, I use 0x10800000.
tftppath is the TFTP path (depends on your configuration)
rootfs_file is the ext4 or ext3 file
Then update the mmc device (you can run mmc listto show SD u-boot number)
mmc dev 2
Here I set the device to the number 2, you need to set it corresponding to the mmc list command.
Then write the content of the RAM to the SD:
setexpr rootfsblksz ${filesize} / 200
setexpr rootfsblksz ${rootfsblksz} + 1
mmc write ${rootfs_addr} 6000 ${rootfsblksz}
Description:
I create a rootfsblksz variable, it converts the number of bytes downloaded to a number of blocks. filesizeis set automatically when we use TFTP, it represents the size of the last downloaded file (in Bytes).
Here my block is 512Bytes (0x200)
I add +1 to the blocksize (to be shure to have all the data)
I write it on the eMMC (or SD) at the address 0x6000 (in blocks) -> 24 576 blocks -> 12 582 912 (in Bytes) -> 12MB because my ext partition is at 12MB offset
Hope it helps!
Depending on a few configurations I tried in /etc/fw_env.config such as one or two entries, I got the following errors when trying to read the U-boot environment variables:
root#varsomam33:~# fw_printenv serverip
Warning: Bad CRC, using default environment
or
root#varsomam33:~# fw_printenv serverip
Cannot read bad block mark: Invalid argument
According to this tutorial (https://developer.ridgerun.com/wiki/index.php/Setting_up_fw_printenv_to_modify_u-boot_environment_variables), I constructed my /etc/fw_env.config to look like this:
# MTD device name Device offset Env. size Flash sector size Number of sectors
/dev/mtd6 0x1C0000 0x20000 0x20000 1
/dev/mtd7 0x1E0000 0x20000 0x20000 1
FYI I'm using a TI Omap ARM chip (var-som-am33) with Yocto Fido default out-of-box from Variscite with these software versions:
U-boot version: u-boot-var-som-am33 2014-+gitrAUTOINC+adf9a14020
U-boot-fw-utils version: u-boot-fw-utils v2014.07+gitAUTOINC+524123a707-r0-arago0-var
The main problem is that "Device offset" is incorrectly described in the RidgeRun tutorial. It is not the absolute offset in NAND flash, but rather the offset from the partition which should be "0x0" in my case.
Here is my working /etc/fw_env.config
root#varsomam33:~# cat /etc/fw_env.config
# MTD device name Device offset Env. size Flash sector size Number of sectors
/dev/mtd6 0x0 0x20000 0x20000 1
/dev/mtd7 0x0 0x20000 0x20000 1
Further, the CRC error I was getting is thrown when there is not a U-boot backup (redundant) environment described in the /etc/fw_env.config file. The fw_printenv utility works by copying the "selected" environment, modifying the variable you have changed, and writing it out to the "new" environment. Then it swaps "selected" and "new".
So if you only have one environment in /etc/fw_env.config, it uses default values for the "selected" environment.
Here is the code tools/env/fw_env.c
1230 crc0_ok = (crc0 == *environment.crc);
1231 if (!HaveRedundEnv) {
1232 if (!crc0_ok) {
1233 fprintf (stderr,
1234 "Warning: Bad CRC, using default environment\n");
1235 memcpy(environment.data, default_environment, sizeof default_environment);
DD is a tool for linux which can Write partial data from MBR.bin to a sector in USB (instead of writing a whole sector). Now I need to do such thing in windows. There is a DD for windows, but it seems it will write a whole sector!
I need to write first 440 bytes of a mbr file to a usb stick. the code in linux is:
dd if=mbr.bin of=/dev/sd<X> bs=440 count=1
and in windows it will be:
dd bs=440 count=1 if=mbr.bin of=\\.\<x>:
where x is the volume letter. But in windows it will cause USB to be corrupted and usb need to be formatted. It seems it writes the whole data. How can I solve this problem?
Copy a complete block!
e.g. for a 512 byte blocksize (512-440=72)
copy mbr.bin mbr.full
dd bs=1 if=\\.\<x>: skip=440 seek=440 of=mbr.full count=72
dd bs=512 if=mbr.full of=\\.\<x>: count=1
Are you sure you pass the parameters correctly? Maybe the win version expects it to be /bs=440. Just a guess. Can't you anyway just truncate the file to 440 bytes?
I have a series of questions on how U-boot works on the BeagleBone Black. Everything started with this tutorial on how to use a micro SD card(uSD) as extra storage.
uSD as extra storage on BBB.
Currently my setup looks like this.
$ fdisk -l
Disk /dev/mmcblk0: 7948 MB, 7948206080 bytes #uSD
Device Boot Start End Blocks Id System
/dev/mmcblk0p1 2048 198655 98304 e W95 FAT16 (LBA)
/dev/mmcblk0p2 198656 15523839 7662592 83 Linux
Disk /dev/mmcbk1: 3867 MB, 3867148288 bytes #eMMC
Device Boot Start End Blocks Id System
/dev/mmcblk1p1 * 2048 198655 98304 e W95 FAT16 (LBA)
/dev/mmcblk1p2 198656 7553023 3677184 83 Linux
So if I havent had it wrong this is what happends.
Boot sequence.
1.The BBB is powered.
2.The U-boot is loaded from the eMMC(/dev/mmcblk1p1)
3.The U-boot searches for uEnv.txt file within the uSD(/dev/mmcblk0p1) and loads it.
...... We will retake from here.
In /dev/mmcblk0p1 i have a uEnv.txt file that looks like this.
mmcdev=1
bootpart=1:2
mmcroot=/dev/mmcblk1p2 ro
optargs=quiet
In /dev/mmcblk1p1 i have the default uEnv.txt file that at some point have this lines.
loadkernel=load mmc ${mmcdev}:${mmcpart} ${loadaddr} ${kernel_file}
loadinitrd=load mmc ${mmcdev}:${mmcpart} ${initrd_addr} ${initrd_file}; setenv initrd_size ${filesize}
.......
mmcargs=setenv bootargs console=tty0 console=${console} ${optargs} ${kms_force_mode} root=${mmcroot} rootfstype=${mmcrootfstype} ${systemd}
We can see how ${mmcdev}, ${mmcroot}, ${optargs} are used although they arent defined in the file, they are defined uSD uEnv.txt.
Question 1.
¿Does this mean that both uEnv.txt files are loaded?
Retaking the boot sequence.
Boot sequence.
4.The U-boot searches for uEnv.txt file within the eMMC(/dev/mmcblk1p1) and loads it.
5.The Linux kernel is loaded.
When there is no uSD the ${mmcdev}, ${mmcroot}, ${optargs} arguments aren't defined, not in the uEnv.txt at least.
Question 2.
¿Where do the default values come?
Now the part that really bothers me. On another board a have a eMMC uEnv.txt file that looks like this.
optargs=quiet drm.debug=7 capemgr.enable_partno=BB-UART2,BB-UART1
The board boots fine without uSD.
Question 3.
How is that even posible?
The answer to the question should be in your board configuration file. Specifically the definition of 'CONFIG_EXTRA_ENV_SETTINGS'- "Define this to contain any number of null terminated strings (variable = value pairs) that will be part of the default environment compiled into the boot image." (from u-boot README file)