Re: [seL4] am335x and question

please ignore my "UART_PPTR" question, I read it backwards, oops. Thank you Jordan, the workaround you mention fixes my MMU problem. I am not sure why. project tools/elfloader/ diff --git a/src/arch-arm/mmu-v7a.S b/src/arch-arm/mmu-v7a.S index ce40478..3b02873 100644 --- a/src/arch-arm/mmu-v7a.S +++ b/src/arch-arm/mmu-v7a.S @@ -62,7 +62,7 @@ arm_enable_mmu: * Setup client to only have access to domain 0, and setup * the DACR. */ - mov r1, #1 + mov r1, #3 // XXX am335x hack, was 1. mcr p15, 0, r1, c3, c0, 0 /* Setup misc MMU. */ the test is now making it to userland, but not for long.. more bugs to hunt... On Fri, Feb 13, 2015 at 10:08 AM, Jordan Woehr wrote:

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 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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-- Tim Newsham | www.thenewsh.com/~newsham | @newshtwit | thenewsh.blogspot.com