Thank you for your help KR!
I also noticed this CONFIG_RAM_START=0x800100. Unfortunately, changing
that value to the proper 0x800200 did not really help the issue.
I went ahead and generated the disassembly like you suggested, and it
does
appear that the .text section starts with jump instructions for all
the
interrupt vectors:
00000000 <_stext>:
0: 0c 94 72 00 jmp 0xe4 ; 0xe4 <__start>
4: 0c 94 95 00 jmp 0x12a ; 0x12a <atmega_int0>
8: 0c 94 98 00 jmp 0x130 ; 0x130 <atmega_int1>
c: 0c 94 9b 00 jmp 0x136 ; 0x136 <atmega_int2>
10: 0c 94 9e 00 jmp 0x13c ; 0x13c <atmega_int3>
14: 0c 94 a1 00 jmp 0x142 ; 0x142 <atmega_int4>
18: 0c 94 a4 00 jmp 0x148 ; 0x148 <atmega_int5>
1c: 0c 94 a7 00 jmp 0x14e ; 0x14e <atmega_int6>
20: 0c 94 aa 00 jmp 0x154 ; 0x154 <atmega_int7>
24: 0c 94 ad 00 jmp 0x15a ; 0x15a
<atmega_pcint0>
28: 0c 94 b0 00 jmp 0x160 ; 0x160
<atmega_pcint1>
2c: 0c 94 b3 00 jmp 0x166 ; 0x166
<atmega_pcint2>
30: 0c 94 b6 00 jmp 0x16c ; 0x16c <atmega_wdt>
34: 0c 94 b9 00 jmp 0x172 ; 0x172
<atmega_tim2_compa>
38: 0c 94 bc 00 jmp 0x178 ; 0x178
<atmega_tim2_compb>
3c: 0c 94 bf 00 jmp 0x17e ; 0x17e
<atmega_tim2_ovf>
40: 0c 94 c2 00 jmp 0x184 ; 0x184
<atmega_tim1_capt>
44: 0c 94 c5 00 jmp 0x18a ; 0x18a
<atmega_tim1_compa>
48: 0c 94 c8 00 jmp 0x190 ; 0x190
<atmega_tim1_compb>
...and so on...
`g_idle_topstack` is 0x800e2b in the disassembly. With RAM_START being
0x800200, and a size of 8192 bytes, that gives a `heap_size` of 5076
bytes.
That all seems fine.
However, printing out the value of `g_idle_topstack` (in binary using
`up_putc`) I can see that the value does not match. The printed value
is
"1000011001110110" while the binary representation of 0x800e2b is
"100000000000111000101011".
Printing out the `heap_size` tells me it's "1111100111001101", which
is
not 5076.
It seems your suspicion about a mismatch is probably correct, although
it's not due to a misplaced vector table it seems.
I did, for fun, try enabling `CONFIG_DEBUG_OPT_UNUSED_SECTIONS` and it
did
remove the vectors at the start of the assembly file. That image
didn't
work.
Then I kept `CONFIG_DEBUG_OPT_UNUSED_SECTIONS` enabled and put the
`KEEP(*(.vectors))` suggestion in the linker script. Vectors are kept
in
the image, and `g_idle_topstack` changes to 0x800be4. This image
didn't
work either.
That got me thinking if there was another section getting unexpectedly
tossed, so I put `KEEP(...)` around basically everything in the linker
script. That didn't produce a different result, and still had the
`g_idle_topstack` of 0x800e2b.
I will continue to debug this, but if you have any other suggestions
please let me know. Thank you very much for all your help so far!
Matteo
On Tue, May 27, 2025 at 7:33 PM <kr....@kerogit.eu> wrote:
Thanks to you as well.
I spotted an error in the config posted both in the issue #16444 and
PR
#16443. It is the
CONFIG_RAM_START=0x800100
Unless I overlooked something, the RAM starts at address 0x200
(0x800200) for AtMega 2560.
Not sure if that's what causing the problem though - as far as I can
see, that value is actually only used as an input to CONFIG_RAM_END
calculation and incorrect value in this macro simply reduces heap
size.
The symptoms of the bug would match though - the program would be
trying
to use I/O registers as RAM.
Thing is - seeing the bug was narrowed down to heap initialization in
nx_start - I remember that I ran into pretty much the same issue when
adding support for AVR DA/DB family... and I can't remember what was
the
problem.
Maybe check the disassembly file? (RAW_DISASSEMBLY needs to be set
for
the file to be generated.) Verify that the .text section starts with
jmp
instructions for interrupt vectors. This is only a vague memory but I
think that I ran into the issue because the linker removed .vectors
section, thinking it was unreferenced. (But that should not happen
here,
the linked config shows CONFIG_DEBUG_OPT_UNUSED_SECTIONS is not set.)
Anyway, when that happened, the whole program got "shifted" - except
for
program memory that stored values of initialized variables. The data
copy loop in initialization code (atmega_head.S) then read the values
from the shifted location leading to a mismatch - variables were
populated with wrong data. One of those variables was g_idle_topstack
which directly sets start of heap. I think it initialized it to
zero...?
Again, all of this is based on vague memory. TLDR version is: if
able,
check g_idle_topstack in up_allocate_heap and verify that it is
correct.
On 2025-05-27 15:28, Alan C. Assis wrote:
> Thank you KR,
>
> I posted your message in that issue for reference.
>
> I have a BK-AVR128 board:
> https://aliexpress.com/item/1005006234334573.html
> and will test NuttX on it to confirm.
>
> If everything is working as expected I will submit the board support to
> the
> mainline.
>
> BR,
>
> Alan
>
> On Tue, May 27, 2025 at 6:39 AM <kr....@kerogit.eu> wrote:
>
>> Hello,
>>
>> as mentioned in one of my previous e-mails to this list (RFC:
>> decoupling
>> ability to always panic from board_reset), I noticed #16444 and #16443
>> on GitHub.
>>
>> I found some time to look into this and I believe I found the reason
>> for
>> "If you add avr_lowputc calls in the board initialization code, you'll
>> see that the TX LED stays stuck on indefinitely."
>>
>> Provided the board initialization code that sentence is talking about
>> is
>> atmega_boardinitialize() in avr_boot.c, then avr_lowputc() likely does
>> not work because of the configuration used. According to #16444, the
>> configuration has:
>>
>> CONFIG_DEV_CONSOLE=y
>> CONFIG_CONSOLE_SYSLOG=y
>>
>> These two are processed in src/atmega/atmega_config.h
>>
>> #ifndef CONFIG_DEV_CONSOLE
>> # undef USE_SERIALDRIVER
>> # undef USE_EARLYSERIALINIT
>> #else
>> # if defined(CONFIG_CONSOLE_SYSLOG)
>> # undef USE_SERIALDRIVER
>> # undef USE_EARLYSERIALINIT
>> # elif defined(HAVE_USART_DEVICE)
>> # define USE_SERIALDRIVER 1
>> # define USE_EARLYSERIALINIT 1
>> # else
>> # undef USE_SERIALDRIVER
>> # undef USE_EARLYSERIALINIT
>> # endif
>> #endif
>>
>> With the configuration above, the outer ifndef is not true and first
>> if
>> defined in else block is true, which results into:
>>
>> undef USE_SERIALDRIVER
>> undef USE_EARLYSERIALINIT
>>
>> Since CONFIG_STANDARD_SERIAL is also set, the undef of
>> USE_SERIALDRIVER
>> is reverted by define USE_SERIALDRIVER 1 later. However,
>> USE_EARLYSERIALINIT remains unset.
>>
>> This causes avr_earlyserialinit() to not be built nor called from
>> avr_lowinit(). Serial port peripheral is therefore not initialized yet
>> when atmega_boardinitialize() is called. I don't know what exactly
>> happens when you attempt to transmit data with the port not enabled
>> but
>> my guess would be that "transmit data register empty" status flag is
>> just never cleared and the program ends up in a loop waiting for that
>> to
>> happen.
>>
>>
>> Other than that - I recently tested NSH on mega1284p-xplained (well, a
>> breadboard with the chip stuck in it actually) and it worked for me.
>> As
>> far as I can see, all AtMega devices use the same code for managing
>> serial ports so it should work out of the box.
>>
>> Someone somewhere in some forum on the net has or had a footer in his
>> posts saying something along the lines of that non-functional serial
>> port is 99% mismatching baud rates, might be worth a re-check.
>>
>> As for the PR itself (copying from e-mail mentioned at the beginning)
>> -
>> I would recommend trying to use KEEP(*(.vectors)) as seen in
>> boards/avr/avrdx/breadxavr/scripts/breadxavr.ld - the default config
>> should then not need the "# CONFIG_DEBUG_OPT_UNUSED_SECTIONS is not
>> set"
>> line.
>>
