I have an application which requires connecting two F&S boards with their default Uboot consoles connected to each other externally. This prevents them from loading the kernel since both of them locks each other by sending characters, since each uboot is waiting with "Hit any key to skip the autoboot".
I don't want to recompile the uboot to change the default console or silent the console. Is there any other solution so that once the uboot has been prevented from auto booting can reenter into the kernel boot state, for instance like booting after a predefined time?
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With freshly flashed L4T 21.8, the serial console stops with output like:
## Flattened Device Tree blob at 82000000
Booting using the fdt blob at 0x82000000
Using Device Tree in place at 82000000, end 83014f2d
Starting kernel ...
How do I get serial output from the kernel?
When things stop after "Starting kernel...", across boards, there are usually two causes:
serial console isn't enabled right
kernel didn't have enough space to unpack itself and start printing to serial console.
The first thing to enable is serial console. Make sure the kernel command line for TK1 includes:
console=ttyS0,115200n8 earlycon=uart8250,mmio32,0x70006300 earlyprintk
Two things are going on there: One is enabling normal serial console once boot gets far enough. The other is enabling earlycon before the proper 8250 driver is initialized, so you can see early boot failures too. This serial setup should get you output on the DB9 connector J1A2 (UART4) just like u-boot uses.
If you still don't have serial output with that, likely the issue is the kernel trashing the dtb while unpacking -- the default 16Mb between 0x81000000 kernel and 0x82000000 fdt is not enough for many kernels. You need to move the fdt address up to make space. Press the reset button, and interrupt the boot by pressing a key when prompted, then enter this in your u-boot command line:
set fdt_addr_r 0x83000000
saveenv
run bootcmd
This gets you 32MB of space for the kernel image for this boot, and thanks to saveenv also any following ones.
I have written an application for defragmenation which starts at boot time.We know every system boots up faster or slower depending on its configuration.I have given hard coded value of 3 seconds during boot time so that,windows registers all ports during that time.I just want to know,are there any APIs existing which gives exact time when windows system is completely ready at boot time.That is whether all USB ports and others got recognized or not.?
I am using TIOMAP/AM3517 based custom board which has ARM7 core + Linux 2.6.32 running on it.
Recently, I started observing an issue in which all the interfaces serial console, RNDIS/USB, Network stops responding (my type on keyboard connected to serial port/console port doesn't go through + no device is detected upon removal/insertion of USB sticks/BT dongle + Ethernet/network activities are stopped (can't login over ssh or access webPage that the system has.
I checked the power to the CPU and other power rails using DMM and it looks fine.
There is no keyboard attached so MagicSysRq cannot be used while the issue happens.
I have watchdog on the system which rebooted the system, however to reproduce the issue and to get more information of the system's state, now i have disabled the watchdog.
Finally, my system/linux is configured to reboot upon detecting softlockup which is not happening either. Also, I have enabled verbose debug options under kernel hacking but nothing seems to give any more information.
How do I debug the issue to identify the rot cause of it?
I am using OMAP3515 processor (Generic CortexA8 Device) for my project and want to boot the system form UART3.
The boot loader code which I am using is working fine when using emulator i.e it is able to write the image into FLASH.
The same boot loader code when I am sending through UART it is executing in RAM but unable to write the image into FLASH.
You may need to unlock the flash. Some systems provide a option to lock and unlock flash.
I am developing an application for linux based embedded system which directly writes on the framebuffer device of the Linux kernel.The writing works perfectly. But the problem happens when some other event occurs with a demand of display(Like plugging a flash drive or a kernel message). Every time when it happens, the screen gets interrupted and the unwanted things appear on the screen erasing the previous graphics from the overlapped portion(other things remain unchanged).
How can I get rid of this problem?
Add console=0 to the kernel command line. It disables both the kernel outputting anything to the console, and the console login. (For development purposes, I recommend having a separate boot option, so you can boot to a console.)
Alternatively, have your application create a new virtual terminal for the framebuffer, like X does. This avoids the kernel (kernel console, really) scribbling text all over your framebuffer.