On Wednesday, February 24, 2016, nick <xerofoify@xxxxxxxxx> wrote:
On 2016-02-23 09:35 AM, Woody Wu wrote:
> Hi,
>
> I am trying to port 3.18 kernel to a S3C2416. Years ago, a guy helped me
> ported a 3.1.0 kernel to the same board, and the guy left and the kernel
> got too old. The guy also ported an u-boot as boot loader to load the 3.1.0
> kernel. I had the source code of the ported u-boot and the 3.1.0 linux.
>
> Now, my problem is that my porting of 3.18 seems not working, I did not see
> any kernel message printed to the first SoC serial port as I expected. As
> long as I can get kernel message printed to the serial, I think I can step
> by step finish the whole porting work eventually. But now, there is no
> message and I have no other hardware debugging tools and knowledges, I felt
> I lost my way totally.
>
> I hope someone can give me some suggestions, clues to help me
> understand where to check and what's the possible causes.
>
Firstly my knowledge with kernel upstream porting to a non mainlined
port is not as good as some of the other people here but let's see what
I can do.
> Since I found the old porting of the 3.1.0 is quit similar to SMDK2416,
> then I started my work from also the SMDK2416 board code in 3.18.
> Basically, I defined the machine-code to match that passed from u-boot, and
> copied the MACHINE-START definition section with removing of some
> not-immediately-needed stuff such as USB, NAND and HMSUI etc. I also
> enabled the S3C2410 serial driver and enabled the serial console supporting
> for the Samsung SoC. Of course, I had the kernel parameter of
> "console=ttySAC0", ttySAC0 is the Linux device name of the first UART port
> in the SoC. These are basically what I had done and I guess the SoC serial
> part between my board and SMDK2416 should be very similar and the kernel
> should at least be able to print it's first message then I should have
> chance to fix other differences. But there is no kernel message at all as I
> mentioned above.
>
Can you either send me the patch series that the other developer used to port
your port to 3.1.0 or I would recommend stating on kernel 3.1.0 as it's still
a longterm kernel unless you have reason to upgrade. If you do I would recommend
you either get something with experience or yourself to try and upstream the
differences between your board and the mainline so others will not have to do
the same work as you unless your company will not allow you to do this.
> What should I check for the problem usually? Is there a checking list to go
> through? I hope you experts can give me some clues. Thanks in advance!
>
To make a patch, I have to have the original 3.1.0, but I was confused about how the kernel.org organized, I just cannot find how to get a 3.1.0 tarball or git repository. Can you please give me a hint? BTW, I also dont really understand what the 'mainline' mens. If I download a latest 3.18.27.tar.xz, is it a mainline?
Their are two things you can do here either try and enable early_printk as this
seems to be happening before the serial console is able to print the first kernel
message. The second is trying to enable kgdb on the board and use another computer
over the serial port to do this sort of debugging.
Hope this gets you started,
Nick
Firstly, I will try early_printk soon. Before that, can your tell me what are differences betweenthe following printing technologies: 1, early_printk 2, early_print, 3, putc used in arch/arm/compressed/misc.c.
Secondly, I have a question about kgdb. You see the situation is that my serial port had been initialized by the u-boot, but not yet touched by the kernel since the kernel is not yet run and waiting for debugging, and now I am jusr sitting in the u-boot command prompt and has an uImage kernel image file loaded in a region of SDRAM, do you think that these all above are enough or possible to the kgdb debugging?
Many thanks!
> Best Regards,
> woody
>
>
>
>
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woody
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