Beaglebone Black FDT issue

[Sebastian Huber]

On 28/06/17 11:04, Sichen Zhao wrote:
> Hi all,
> I have a issue about BBB FDT: I add " bl bsp_fdt_copy " in c/src/lib/libbsp/arm/shared/start/start.S,  when my test exe(modify the testsuites/libtests/libfdt01) boot,  came out a error: data abort.
>
> Boot output error info:
>
> data abort
> pc : [<80000df0>]          lr : [<8000004c>]
> sp : 9f62a960  ip : ffffffff     fp : 9f7a34ec
> r10: 00000000  r9 : 9f62af28     r8 : 9f633714
> r7 : 00000000  r6 : 88000000     r5 : 00000e05  r4 : 800158ac
> r3 : 0002ad24  r2 : 88000000     r1 : 00000e05  r0 : 00000000
> Flags: nzcv  IRQs off  FIQs on  Mode SVC_32
> Resetting CPU ...
>                                                                                  
> resetting ...
>
>
>
> I set the BSP_FDT_BLOB_SIZE_MAX 262144 bytes.
>
> I disassemble my test binary and take a look at the start.S, the info show below:
>
> 80000040 <_start>:
>          /*
>           * We do not save the context since we do not return to the boot
>           * loader but preserve r1 and r2 to allow access to bootloader parameters
>           */
> #ifndef BSP_START_NEEDS_REGISTER_INITIALIZATION
>          mov     r5, r1          /* machine type number or ~0 for DT boot */
> 80000040:       e1a05001        mov     r5, r1
>          mov     r6, r2          /* physical address of ATAGs or DTB */
> 80000044:       e1a06002        mov     r6, r2
> #else /* BSP_START_NEEDS_REGISTER_INITIALIZATION */
>          bl bsp_start_init_registers_core
> #endif
>
> #ifdef U_BOOT_USE_FDT
>          bl bsp_fdt_copy

You have

void bsp_fdt_copy(const void *src);

The first parameter on ARM is passed in register 0. So, r0 must point to 
your FDT.

-- 
Sebastian Huber, embedded brains GmbH

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