I'm experimenting with nanopi board with ubuntu OS and u-boot bootloader.
When booted into system, I set u-boot environment variable with fw_setenv:
$ fw_setenv foo bar
On the following reboot I'd like to access this foo variable from the /boot/boot.scr script:
if [ -z "${foo}" ]; then
echo "Fail"
else
echo "Ok"
fi
I get Fail, so foo is inaccessible.
I've no experience with u-boot but I read that it has two sets of environment variables: one read-only (fixed as a part of U-boot image), and another read/write (user environment). So it looks like user environment is not accessible from boot.scr script? Is it true? How can I make my foo variable visible at the moment when boot.scr is executed?
Upd: My /etc/fw_env.config file:
# Block device
/dev/mmcblk1 0xc0000 0x20000
U-boot version: 2020.01
The problem is found. U-boot constants CONFIG_SYS_MMC_ENV_DEV, CONFIG_ENV_OFFSET, and CONFIG_ENV_SIZE did not match those in /etc/fw_env.config.
Solved the problem by changing these constants to
#define CONFIG_SYS_MMC_ENV_DEV 1
#define CONFIG_ENV_OFFSET 0x3f8000
#define CONFIG_ENV_SIZE 0x20000
recompiling u-boot and updating fw_env.config accordingly:
/dev/mmcblk1 0x3f8000 0x20000
Related
I'm trying to use the kernel's cpuset to isolate my process. To obtain this, I follow the instructions(2.1 Basic Usage) from kernel doc cpusets, however, it didn't work in my environment.
I have tried in both my centos7 server and my ubuntu16.04 work pc, but neither did work.
centos kernel version:
[root#node ~]# uname -r
3.10.0-327.el7.x86_64
ubuntu kernel version:
4.15.0-46-generic
What I have tried is as follows.
root#Latitude:/sys/fs/cgroup/cpuset# pwd
/sys/fs/cgroup/cpuset
root#Latitude:/sys/fs/cgroup/cpuset# cat cpuset.cpus
0-3
root#Latitude:/sys/fs/cgroup/cpuset# cat cpuset.mems
0
root#Latitude:/sys/fs/cgroup/cpuset# cat cpuset.cpu_exclusive
1
root#Latitude:/sys/fs/cgroup/cpuset# cat cpuset.mem_exclusive
1
root#Latitude:/sys/fs/cgroup/cpuset# find . -name cpuset.cpu_excl
usive | xargs cat
0
0
0
0
0
1
root#Latitude:/sys/fs/cgroup/cpuset# mkdir my_cpuset
root#Latitude:/sys/fs/cgroup/cpuset# echo 1 > my_cpuset/cpuset.cpus
root#Latitude:/sys/fs/cgroup/cpuset# echo 0 > my_cpuset/cpuset.mems
root#Latitude:/sys/fs/cgroup/cpuset# echo 1 > my_cpuset/cpuset.cpu_exclusive
bash: echo: write error: Invalid argument
root#Latitude:/sys/fs/cgroup/cpuset#
It just printed the error bash: echo: write error: Invalid argument.
Google it, however, I can't get the correct answers.
As I pasted above, before my operation, I confirmed that the cpuset root path have enabled the cpu_exclusive function and all the cpus are not been excluded by other sub-cpuset.
By using ps -o pid,psr,comm -p $PID, I can confirm that the cpus can be assigned to some process if I don't care cpu_exclusive. But I have also proved that if cpu_exclusive is not set, the same cpus can also be assigned to another processes.
I don't know if it is because some pre-setting are missed.
What I expected is "using cpuset to obtain exclusive use of cpus". Can anyboy give any clues?
Thanks very much.
i believe it is a mis-understanding of cpu_exclusive flag, as i did. Here is the doc https://www.kernel.org/doc/Documentation/cgroup-v1/cpusets.txt, quoting:
If a cpuset is cpu or mem exclusive, no other cpuset, other than
a direct ancestor or descendant, may share any of the same CPUs or
Memory Nodes.
so one possible reason you have bash: echo: write error: Invalid argument, is that you have some other cgroup cpuset enabled, and it conflicts with your operations of echo 1 > my_cpuset/cpuset.cpu_exclusive
please run find . -name cpuset.cpus | xargs cat to list all your cgroup's target cpus.
assume you have 12 cpus, if you want to set cpu_exclusive of my_cpuset, you need to carefully modify all the other cgroups to use cpus, eg. 0-7, then set cpus of my_cpuset to be 8-11. After all these cpus configurations , you can set cpu_exclusive to be 1.
But still, other process can still use cpu 8-11. Only the tasks that belongs to the other cgroups will not use cpu 8-11
for me, i had some docker container running, which prevents me from setting my cpuset cpu_exclusive
with kernel doc, i do not think it is possible to use cpus exclusively by cgroup itself. One approach (i know this approach is running on production) is that we isolate cpus, and manage the cpu affinity/cpuset by ourselves
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);
I am using an arm board using TFTP and NFS but it got stuck at kernel loading as shown in the screenshot and I have to input the run uenvcmd then the process will keep going and everything is OK.
Below is my uEnv.txt:
# This uEnv.txt file can contain additional environment settings that you
# want to set in U-Boot at boot time. This can be simple variables such
# as the serverip or custom variables. The format of this file is:
# variable=value
# NOTE: This file will be evaluated after the bootcmd is run and the
# bootcmd must be set to load this file if it exists (this is the
# default on all newer U-Boot images. This also means that some
# variables such as bootdelay cannot be changed by this file since
# it is not evaluated until the bootcmd is run.
autoload=no
ipaddr=192.168.1.100
serverip=192.168.1.13
gatewayip=192.168.1.1
staticip=${ipaddr}:${serverip}:${gatewayip}:255.255.255.0:::off
bootpath=/tftpboot
rootfspath=/opt/ti-processor-sdk-linux-rt-am57xx-evm-03.00.00.04/targetNFS
#setting for kernel loading
kernel_addr=0x82000000
fdt_addr=0x88000000
nfs_args=setenv bootargs console=ttyO0,115200n8 root=/dev/nfs rw nfsroot=${serverip}:${rootfspath} ip=${staticip}
load_zimage=tftp ${kernel_addr} ${bootpath}/zImage
loadfdt=tftp ${fdt_addr} ${bootpath}/am572x-idk.dtb
boot_zimage=bootz ${kernel_addr} - ${fdt_addr}
uenvcmd=run load_zimage; run loadfdt; run nfs_args; run boot_zimage
these is a strange file called uboot.env beside the uEnv.txt, too long to paste here, uboot.env
Problem solved: Just delete the file uboot.env
This should be a bug of SDK. I will report this to TI. Thanks #Notlikethat
I have some question about Linux kernel and GPIOs. I know that in Linux everything is file so when I do something like
echo 30 > /sys/class/gpio/export
and
echo 1 > /sys/class/gpio/gpio30/value
what really happens? I mean how does sysfs handle that? Does it call system calls implemented in gpiolib?
The gpiolib registers the value attribute in this way:
static const DEVICE_ATTR(value, 0644, gpio_value_show, gpio_value_store);
It creates a device attribute named value, with permission 644; on read it calls gpio_value_show, on write it calls gpio_value_store
What sysfs does, is to redirect read and write to the correspondent function of a sysfs attribute.
Does anyone know of a way to get U-boot version installed from userspace? There is the fw_printenv command that provides access to U-boot's environment variables, but not the version.
If U-boot is located in mtd0, you can get version info as follows:
root#SUPERWIFI:/proc# strings /dev/mtd0 | grep U-Boot
U-Boot 1.1.4-g1c8343c8-dirty (Feb 28 2014 - 13:56:54)
U-Boot
Now running in RAM - U-Boot at: %08lx
Just an update for this.
In our version of U-Boot we changed the code for main_loop() in main.c to this:
#ifdef CONFIG_VERSION_VARIABLE
char *oldver=getenv("ver");
if(oldver==0 ||strcmp(oldver,version_string))
{
setenv("ver", version_string); /* set version variable */
saveenv();
}
#endif /* CONFIG_VERSION_VARIABLE */
So setenv/saveenv is only called, if needed by an update.
In our firmware we added
/sbin/fw_printenv -n ver > /var/config/u-boot.ver
to make the u-boot version public available.
There's no defined way to do this. Once Linux boots, u-boot is no longer running and it's RAM is reclaimed for Linux's use. Linux doesn't even know about u-boot. Nor does it have to have been booted by u-boot.
If you really want to do this, the only way to do it is to add the u-boot version to the kernel's command line, write code to scan the u-boot image in flash for it's version, or something even nastier.
An alternative solution is to read the version directly from the u-boot binary file (can be even embedded in an image file containing other binaries as well like e.g. the first stage bootloader) with e.g. mmcblk0boot0 as partition (of device mmcblk0) the bootloader resides in:
sudo grep -a --null-data U-Boot /dev/mmcblk0boot0
Site note: Does work not only for Arch Linux but e.g. Ubuntu as well.
In my devices UBoot automatically creates a "ver" environment variable containing its version:
U-Boot > printenv
baudrate=115200
ethact=FEC ETHERNET
ethaddr=24-db-ad-00-00-08
bootdelay=3
bootcmd=bootm fc080000 - fc060000
bootargs=console=ttyCPM0,115200n8 rdinit=/sbin/init
stdin=serial
stdout=serial
stderr=serial
ver=U-Boot 2009.03-svn9684 (Mar 08 2010 - 17:08:32)
Environment size: 253/131068 bytes
U-Boot >
I don't use fw_printenv, but I would imagine that this variable gets passed along as well. Maybe you already have something similar in your system?
UPDATE (5/23/2012):
I added fw_printenv to my linux image and can confirm that I do see the "ver" variable:
[root#ST600 /]# fw_printenv
baudrate=115200
ethact=FEC ETHERNET
ethaddr=24-db-ad-00-00-08
stdin=serial
stdout=serial
stderr=serial
ver=U-Boot 2009.03-svn9684 (Mar 11 2010 - 09:43:08)
bootcmd=bootm fc080000 - fc060000
bootdelay=3
bootargs=console=ttyCPM0,115200n8 rdinit=/sbin/init panic=10 mem=32m
[root#ST600 /]#
Try to read uboot version this way:
Find uboot partition, eg. for MTD device:
cat /proc/mtd
For /dev/mtd5:
cat /dev/mtd5 | hexdump -C -n 64
You can't rely on fw_printenv if you want to know u-boot version.
fw_printenv just looks for the printenv partition and dumps its data. So it's OK for normal variables, but it's not OK for the "ver" variable, which is dynamic, and whose value is initialized by u-boot when it boots. The value of this variable doesn't remain after u-boot exit, except if you manually save it to environment.
For example, on my board, if I print the "ver" variable from u-boot prompt:
U-Boot > printenv ver
ver=U-Boot 2009.11-00393-g5ca9497-dirty (Nov 26 2012 - 11:08:44)
This is the real version of u-boot, coming from u-boot itself.
Now, if I boot my board and use fw_printenv:
el#board # fw_printenv | grep ver=
ver=U-Boot 2009.11-00323-gbcc6e0e (Sep 21 2012 - 11:07:19)
As you can see, it's different. Because it happens that I have a "ver" variable defined in my environment. And it doesn't match the real u-boot version.
Of course, I could go back to u-boot, use "saveenv" to update the "ver" value in the environment. Then the two values would match. But then, I should always update the environment after changing u-boot.
So, my conclusion is that using fw_printenv to get u-boot version is definitely not a good idea.
If u-boot is residing in an MTD partition then this will work:
U_BOOT_VER=$(for part in `grep u-boot-[01] /proc/mtd | cut -f 1 -d ':'`; do strings /dev/${part} | grep "^U-Boot.*("; break; done)