Debugging VoCore2 ROM Startup

[Stefan Roese]

Hi Mauro,

On 15.01.20 18:25, Mauro Condarelli wrote:
>>>
>>>>> Note: I assumed u-boot-mtmips.bin is linked at 9c000000, right?
>>>>
>>>> You don't need to know where it is linked to if you program it into
>>>> SPI NOR. But yes, the first stage the SPL is linked to 0x9c000000.
>>> Can You elaborate, please?
>>
>> Each image generated to boot from SPI NOR needs to be linked to 9c000000.
>> This is what the ROM image (non-RAM) of mainline does and the SPL image
>> of the dual image version (SPL plus main U-Boot proper) does.
>>
>>> I know for sure that if I flash at 30000 a u-boot that has been compiled
>>> with SYS_TEXT_BASE = 0x9c000000 it will not start with "go 9c030000"
>>> I need to rebuild with SYS_TEXT_BASE = 0x9c030000.
>>
>> But you flash at offset 0 in SPI NOR, right? That's where the SoC starts
>> reading the bootloader binary after a reset or on power-up.
> I was trying to say that, in my "secondary u-boot" attempts, where I
> start from "paleolithic" and then do a "go <addr>" I need to put the
> secondary at the same address specified in SYS_TEXT_BASE.
> I mean:
> if I want to boot directly from new then
>      SYS_TEXT_BASE = 0x9c000000
>      flash at start of SPI NOR
>      go 9c000000
> else if I want to start "secondary" then
>      SYS_TEXT_BASE = 0x9c030000
>      flash at offset 30000 in SPI NOR
>      go 9c030000
> Any other combination does not work (i.e.: I cannot flash and run at
> start an u-boot compiled with SYS_TEXT_BASE = 0x9c030000 and
> vice versa).
> 
> Note: I had to edit directly .config to change SYS_TEXT_BASE, apparently
> it is visible in menuconfig only for ARM; am I missing something?

I can change it for my LinkIt target via "make menuconfig". Just search
for it by entering "/" in "make menuconfig" and it should show up there.

>>   
> ===8<------
> 
> I do have a led I can use for crude signalling, but I'm not really familiar
> with mips Assembly.
> Can You share the code to turn it on? (it is connected to
> GPIO44/WLED(pin144).

i don't remember but it might be the case. Here the code snippet that
I used at that time. Perhaps it helps:

+#if 0 // test-only: WLAN LED on
+#define RALINK_SYSCTL_BASE		0xB0000000
+	// GPIO mode
+	li	t0, RALINK_SYSCTL_BASE + 0x64
+	li	t1, 0x05540551
+	sw	t1, 0(t0)
+
+	// GPIO direction
+	li	t0, RALINK_SYSCTL_BASE + 0x604
+	li	t1, 0x00001000
+	sw	t1, 0(t0)
+
+	// GPIO value
+	li	t0, RALINK_SYSCTL_BASE + 0x624
+	li	t1, 0x0002f5f
+	sw	t1, 0(t0)
+#endif

Thanks,
Stefan