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<noinclude>{{ApplicableFor
|MPUs list=STM32MP13x, STM32MP15x
|MPUs checklist=STM32MP13x,STM32MP15x
}}</noinclude>
== Debug with console ==
== Debug with console ==
Trace and error are available on the console defined in the '''chosen''' node of the device tree by the '''stdout-path''' field, for example on serial0=uart4:


  chosen {
See {{DocSource | domain=U-Boot |path=develop/logging.html | text=U-Boot Documentation}} or {{CodeSource | U-Boot |doc/develop/logging.rst}} for U-Boot logging details.
  stdout-path = " {{Highlight|serial0}}:115200n8";
  };
  aliases {
  {{Highlight|serial0}} = &{{Highlight|uart4}};
  };


By default, the macros used by U-Boot (debug(), pr_debug()...) do not print any trace; to activate the debug traces on a specific file, you need to enable the '''DEBUG''' compilation flag and change the LOGLEVEL for the file:
'''CONFIG_LOG''' is enable in OpenSTLinux.
* define DEBUG before any include in the <file>.c file
 
By default, traces are available on the U-Boot console which use <code>stdout-path</code> defined in the <code>chosen</code> node of the Linux kernel device tree as described in the Linux kernel binding<ref>{{CodeSource | Linux kernel | Documentation/devicetree/bindings/chosen.txt | Documentation/devicetree/bindings/chosen.txt}} the Linux kernel binding for chosen node</ref>.
 
See page [[How_to_configure_U-Boot_for_your_board#Console|How to configure U-Boot for your board]] for configuration details.
 
The ST boards use the default logging configuration:
* {{highlight|CONFIG_LOG_DEFAULT_LEVEL}} = {{highlight|CONFIG_LOG_MAX_LEVEL}} =  {{highlightParam|LOGL_INFO}} = {{highlightParam|6}}<br/>the 'debug' macros used by U-Boot (log_debug(), debug(), pr_debug()...) are removed in the U-Boot binary.
* CONFIG_LOGF_FILE, CONFIG_LOGF_LINE, CONFIG_LOGF_FUNC are not activated<br/>no debug information in log messages by default.
 
To enable all the debug traces in U-Boot you need to increase the max logging level with a major impact on U-Boot size; e.g. set {{highlight|CONFIG_LOG_MAX_LEVEL}} to {{highlightParam|LOGL_DEBUG}} by adding in your defconfig file the line:
 
  {{highlight|CONFIG_LOG_MAX_LEVEL}}={{HighlightParam|7}}
 
When the traces are present in U-Boot, you can change the default trace level with {{highlight|CONFIG_LOG_DEFAULT_LEVEL}} or you can use the <code>log</code> command (CONFIG_CMD_LOG) to dynamically configure and filter the output:
 
  {{U-Boot$}}  log level 7
  {{U-Boot$}}  log format all
 
=== Activate debug trace on one file ===
 
To turn on this debug logging just in one file, you can define LOG_DEBUG and DEBUG for this file  
 
* add define before any include in the <file>.c file
  #define LOG_DEBUG
   #define DEBUG
   #define DEBUG
  #undef CONFIG_LOGLEVEL
  #define CONFIG_LOGLEVEL 8


* with a Makefile
* with a Makefile
   CFLAGS_<file>.o+= -DDEBUG -DCONFIG_LOGLEVEL=8
   CFLAGS_<file>.o+= -DLOG_DEBUG  -DDEBUG
 
=== Debug before console ===


If U-Boot fails before the console configuration (in the first stage of U-Boot execution), trace is not available.
If U-Boot fails before the console configuration (in the first stage of U-Boot execution), trace is not available.
Line 27: Line 48:
*** {{Highlight|CONFIG_DEBUG_UART}}
*** {{Highlight|CONFIG_DEBUG_UART}}
*** {{Highlight|CONFIG_DEBUG_UART_STM32}}
*** {{Highlight|CONFIG_DEBUG_UART_STM32}}
** adpat the function {{Highlight|board_debug_uart_init()}}: that configures the required resources (pad, clock) before initialization by the U-Boot driver.<br/>This function needs to be adapted for your board.
** adapt the function {{Highlight|board_debug_uart_init()}}: that configures the required resources (pad, clock) before initialization by the U-Boot driver.<br/>This function needs to be adapted for your board.


== Debug with GDB ==
== Debug with GDB ==
Line 36: Line 57:


Or for manual GDB connection, you need to:
Or for manual GDB connection, you need to:
# get the [[U-Boot_overview#Output_files|elf files]] for U-Boot and/or SPL<br/>(u-boot and u-boot-spl available in the build directory)
# get the [[U-Boot_overview#Output_files|elf files]] for U-Boot = <code>u-boot</code> available in the build directory
# connect [[GDB]] to the target
# connect [[GDB]] to the target
# '''reset with attach''' the target with the gdb {{Highlight|"monitor reset halt"}} command:<br/>execution is stopped in ROM code or at the beginning of FSBL execution.
# '''reset with attach''' the target with the gdb {{Highlight|"monitor reset halt"}} command:<br/>execution is stopped in ROM code or at the beginning of FSBL execution.
# load the symbols of the binary to be debugged with commands available in next chapter:<br/>[[#Load U-Boot symbol]], [[#Load SPL symbol]],  [[#Load SPL code and debug]]
# load the symbols of the binary to be debugged with commands available in next chapter:<br/>[[#Load U-Boot symbol]]
# start execution with the {{Highlight|"continue"}} command
# start execution with the {{Highlight|"continue"}} command


=== Load U-Boot symbol ===
=== Load U-Boot symbol ===


With [[U-Boot_overview#U-Boot_phases|U-Boot relocation]], symbols are more difficult to load.
With [[U-Boot_overview#U-Boot_execution_sequence|U-Boot relocation]], symbols are more difficult to load, see {{CodeSource | U-Boot | doc/README.arm-relocation}} for details.  
 
See https://www.denx.de/wiki/DULG/DebuggingUBoot


If you connect GDB on running target, you can load the debug symbols:
If you connect GDB on running target, you can load the debug symbols:
Line 61: Line 80:
The following GDB example script automatically loads the U-Boot symbol before and after relocation for a programmed board, after {{Highlight|"monitor reset halt"}} command:
The following GDB example script automatically loads the U-Boot symbol before and after relocation for a programmed board, after {{Highlight|"monitor reset halt"}} command:


   {{GDB$}} thbreak *0xC0100000
   {{GDB$}} thbreak *{{HighlightParam|0xC0100000}}
   {{GDB$}} commands
   {{GDB$}} commands
   > symbol-file u-boot
   > symbol-file u-boot
Line 77: Line 96:
   > end
   > end


This script uses a temporary hardware breakpoint {{Highlight|"thbreak"}} to load the symbol when U-Boot code is loaded in DDR by FSBL = TF-A or SPL at the U-Boot entry point (CONFIG_SYS_TEXT_BASE = 0xC0100000).
This script uses a temporary hardware breakpoint {{Highlight|"thbreak"}} to load the symbol when U-Boot code is loaded in DDR by FSBL = TF-A at the U-Boot entry point, CONFIG_SYS_TEXT_BASE =
* {{HighlightParam|0xC0000000}} for {{MicroprocessorDevice | device=13}}
* {{HighlightParam|0xC0100000}} for {{MicroprocessorDevice | device=15}}


It allows the symbol to be loaded only when code is executed to avoid DDR access before DDR initialization.
It allows the symbol to be loaded only when code is executed to avoid DDR access before DDR initialization.


=== Load SPL symbol ===
== References ==
 
<references/>
To debug SPL with GDB on a Flashed device, ROM code loads the binary and the GDB script just loads the SPL symbols:
 
  {{GDB$}} symbol-file u-boot-spl
 
=== Load SPL code and debug ===
 
Sometimes you need to debug SPL execution on an unprogrammed target (for example for board bring-up), so you can use GDB to load the SPL code in embedded RAM and execute it.
 
When execution is stopped in ROM code, you need to execute the {{Highlight|"load"}} commands, depending on the compilation flags defined in [[U-Boot_overview#Device_tree|U-Boot device tree]] to load the SPL code and the associated device tree:
 
* CONFIG_OF_SEPARATE = dtb appended at the end of the code, not present in the elf file (default configuration)
 
  {{GDB$}} file u-boot-spl
  {{GDB$}} load
  {{GDB$}} set $dtb =  __bss_end
  {{GDB$}} restore spl/dt.dtb binary $dtb
 
* CONFIG_OF_EMBED = dtb embedded in the elf file (debug configuration)
 
  {{GDB$}} file u-boot-spl
  {{GDB$}} load
 
=== Debug the first SPL instructions ===
 
Sometime the SPL code execution is stopped by the gdb command "monitor reset halt"  after the first instructions.
 
To debug this part, you can modify the code: add a infinite loop in SPL code to wait the gdb connection.
 
For example in {{CodeSource | U-Boot | arch/arm/mach-stm32mp/spl.c}} :
 
<syntaxhighlight lang="c">
void board_init_f(ulong dummy)
{
struct udevice *dev;
int ret;
 
/* volatile is needed to avoid gcc optimization */
volatile int stop = 0;
/* infinite debug loop */
while ( !stop ) ;
 
arch_cpu_init();
</syntaxhighlight>
 
when gdb is attached and the SPL symbols are loaded, the infinite loop is interrupted by :
 
  {{GDB$}} set var stop=1
 
And you can debug the SPL first instruction by gdb commands.


<noinclude>
<noinclude>
[[Category:U-Boot]]
[[Category:U-Boot|U-Boot - 8]]
[[Category:Tracing tools]]
[[Category:Tracing tools]]
[[Category:Debugging tools]]
[[Category:Debugging tools]]
{{PublicationRequestId | 12894 | 2019-08-01}}
{{PublicationRequestId | 12894 | 2019-08-01}}
</noinclude>
</noinclude>

Latest revision as of 15:01, 2 November 2022↑

Applicable for STM32MP13x lines, STM32MP15x lines

1. Debug with console↑

See U-Boot Documentation or doc/develop/logging.rst for U-Boot logging details.

CONFIG_LOG is enable in OpenSTLinux.

By default, traces are available on the U-Boot console which use stdout-path defined in the chosen node of the Linux kernel device tree as described in the Linux kernel binding[1].

See page How to configure U-Boot for your board for configuration details.

The ST boards use the default logging configuration:

  • CONFIG_LOG_DEFAULT_LEVEL = CONFIG_LOG_MAX_LEVEL = LOGL_INFO = 6
    the 'debug' macros used by U-Boot (log_debug(), debug(), pr_debug()...) are removed in the U-Boot binary.
  • CONFIG_LOGF_FILE, CONFIG_LOGF_LINE, CONFIG_LOGF_FUNC are not activated
    no debug information in log messages by default.

To enable all the debug traces in U-Boot you need to increase the max logging level with a major impact on U-Boot size; e.g. set CONFIG_LOG_MAX_LEVEL to LOGL_DEBUG by adding in your defconfig file the line: 

 CONFIG_LOG_MAX_LEVEL=7

When the traces are present in U-Boot, you can change the default trace level with CONFIG_LOG_DEFAULT_LEVEL or you can use the log command (CONFIG_CMD_LOG) to dynamically configure and filter the output: 

   log level 7
   log format all

1.1. Activate debug trace on one file↑

To turn on this debug logging just in one file, you can define LOG_DEBUG and DEBUG for this file

  • add define before any include in the <file>.c file
 #define LOG_DEBUG
 #define DEBUG
  • with a Makefile
 CFLAGS_<file>.o+= -DLOG_DEBUG  -DDEBUG

1.2. Debug before console↑

If U-Boot fails before the console configuration (in the first stage of U-Boot execution), trace is not available.

In this case, you need to:

  • debug with GDB (see the next chapter)

or,

  • activate the debug UART feature:
    • add in defconfig of U-Boot configuration
      • CONFIG_DEBUG_UART
      • CONFIG_DEBUG_UART_STM32
    • adapt the function board_debug_uart_init(): that configures the required resources (pad, clock) before initialization by the U-Boot driver.
      This function needs to be adapted for your board.

2. Debug with GDB↑

With OpenSTLinux, you can directly use GDB script Setup.gdb:

Or for manual GDB connection, you need to:

  1. get the elf files for U-Boot = u-boot available in the build directory
  2. connect GDB to the target
  3. reset with attach the target with the gdb "monitor reset halt" command:
    execution is stopped in ROM code or at the beginning of FSBL execution.
  4. load the symbols of the binary to be debugged with commands available in next chapter:
    #Load U-Boot symbol
  5. start execution with the "continue" command

2.1. Load U-Boot symbol↑

With U-Boot relocation, symbols are more difficult to load, see doc/README.arm-relocation for details.

If you connect GDB on running target, you can load the debug symbols:

  • Before relocation with "symbol-file" command:
  symbol-file u-boot
  • After relocation with "add-symbol-file" command to relocate the symbol with the code offset = gd->relocaddr:
  symbol-file u-boot                            --> only for "gd_t" definition
  set $offset = ((gd_t *)$r9)->relocaddr        --> get relocation offset
  symbol-file                                   --> clear previous symbol 
  add-symbol-file u-boot $offset

The following GDB example script automatically loads the U-Boot symbol before and after relocation for a programmed board, after "monitor reset halt" command: 

  thbreak *0xC0100000
  commands
 > symbol-file u-boot
 > thbreak relocate_code
 > commands
   > print "RELOCATE U-Boot..."
   > set $offset = ((gd_t *)$r9)->relocaddr
   > print $offset
   > symbol-file
   > add-symbol-file u-boot $offset
   > thbreak boot_jump_linux
   > continue
   > end
 > continue
 > end

This script uses a temporary hardware breakpoint "thbreak" to load the symbol when U-Boot code is loaded in DDR by FSBL = TF-A at the U-Boot entry point, CONFIG_SYS_TEXT_BASE =

  • 0xC0000000 for STM32MP13x lines More info.png
  • 0xC0100000 for STM32MP15x lines More info.png

It allows the symbol to be loaded only when code is executed to avoid DDR access before DDR initialization.

3. References↑

  1. ↑ Documentation/devicetree/bindings/chosen.txt the Linux kernel binding for chosen node


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