[seL4] am335x and question

Jordan Woehr jordanwoehr at gmail.com
Sat Feb 14 07:08:44 EST 2015


Hi Tim,

I believe I recently ran into the same problem as you on the am335x. I
posted it to the mailing list, see
http://sel4.systems/pipermail/devel/2015-January/000167.html

Unfortunately I haven't found a solution to the problem yet except for
working around it by modifying domain access bits in the MMU to allow full
access instead of kernel access. I must be overlooking something because I
would expect what is currently in the elfloader to work. After making this
modification I am able to boot into the kernel successfully (I'm booting
directly into the kernel though and not using seL4-test).

The check for UART_PPTR < virt_region_start should be true on the am335x
but may not be for other platforms.

Jordan

On Fri, Feb 13, 2015 at 12:59 PM, Tim Newsham <tim.newsham at gmail.com> wrote:

> I'm playing around with the am335x code now and have the
> sel4 test building but not working properly.  If anyone else is
> interested in playing with this, let me know.
>
> I have a question about the boot loader, I'm seeing:
>
>     if (UART_PPTR < kernel_info.virt_region_start) {
>         printf("Jumping to kernel-image entry point...\n\n");
>     } else {
>         /* Our serial port is no longer accessible */
>     }
>
> is this necessary?  It looks like init_boot_pd established a
> 1:1 mapping for all addresses lower than the kernel vaddr
> (which for me is 0xf0000000). Shouldnt the UART be accesible
> here?
>
> I'm seeing the bootloader run up to mmu is turned on but nothing
> after that and trying to track down where the failure is happening.
> printf's after arm_enable_mmu are not working for me, and I don't
> understand if this is due to mmu bringup problems or something else.
>
> By the way, I started a "#seL4" channel on freenode IRC.
>
> --
> Tim Newsham | www.thenewsh.com/~newsham | @newshtwit |
> thenewsh.blogspot.com
>
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>
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