This project makes two things:
- Simplifies setup of openwrt repository on local machine by avoiding inconsistency and incompatibility of different packages required to be installed to compile OpenWrt image for imx6ull NetSoM
- Setups Eclipse as graphical IDE that lets to:
- navigate through source code using GUI instead command line utilities like grep and find.
- debug u-boot, kernel (not implemented yet) using external J-Link USB debugger connected to the NetSoM Development Board using JTAG interface:
- debug user layer application using onboard gdb server.
- Compile images
- Debugging U-boot
- Debugging Linux Kernel
- Debugging U-boot and Kernel in same session
- IDE typical scenarios
- Development guides
Clone the repository:
https://github.com/wireless-road/openwrt-ide/tree/openwrt-2021.02
Open docker-compose.yml and replace left side of - /home/al/docker/ide/:/opt/eclipse/ volume declaration to the path you want openwrt sources and eclipse to be placed.
Create that folder on host machine.
Then build a container:
$ docker-compose run --name openwrt openwrt
as a result you should get access to container's console. Next you have to setup Eclipse and openwrt sources by running:
$ . ./setup_ide.sh
Pay attention to "dot space dot slash" notation to execute script in current shell without foring a sub shell.
It makes few things:
- clones OpenWrt sources from imx6ull-openwrt
- build simpliest device configuration image to get toolchain compiled.
- installs eclipse.
After finishing you may find /opt/eclipse with inner eclipse and imx6ull-openwrt folders.
As eclipse has very limited possibilities for creation and configuration projects from command line but luckely it is portable we did a trick:
installed Eclipse on host machine at same path (/opt/eclipse/eclipse), created project from existing makefile project for u-boot sources (kernel project to be added soon, I hope), packet resulted folder to archive and here is preconfigured Eclipse installer. So don't move eclipse and imx6ull-openwrt folders to different pathes as it will brake Eclipse`s projects.
So after you finished setup (just once) you can start to work with source code using command line or eclipse GUI.
just move to source code folder:
$ cd /opt/eclipse/imx6ull-openwrt
and here as usual like on the host machine:
$ ./compile.sh list
$ ./compile.sh <any available configuration>
the only pros of using docker image in that case is fastest way to getting started: no need to deal with possible troubles that might happens on requirements installation or sources compilation.
launch eclipse:
$ /opt/eclipse/eclipse/eclipse
Import existing project you want to work on as existing Makefile project. Guides to do that might be found here and here.
Pre-installed u-boot and Linux kernel project might be found on Eclipse opening:
right click on project and press to Clean Project.
right click on project and press to Build Project:
0. Compile u-boot first:
$ cd ~
$ ./compile_uboot_debuggable.sh
1. Start GDB server:
$ jl_server
2. Start GDB session:
$ cd /opt/eclipse/imx6ull-openwrt/build_dir/target-arm_cortex-a7+neon-vfpv4_musl_eabi/u-boot-wirelessroad_ecspi3/u-boot-2020.10/
$ jl_uboot
3. Use /gdb_script/u-boot.txt script to debug U-boot:
3.1. connect to remote target and load image:
(gdb) set confirm off
(gdb) target remote localhost:2331
Remote debugging using localhost:2331
Cannot access memory at address 0x8000004
Cannot access memory at address 0x8000000
Cannot access memory at address 0x8000004
0x8ff5cfc4 in ?? ()
(gdb) monitor reset
Resetting target
(gdb) monitor halt
(gdb) monitor sleep 200
Sleep 200ms
(gdb) load
Loading section .text, size 0x3a8 lma 0x87800000
Loading section .efi_runtime, size 0xf68 lma 0x878003a8
Loading section .text_rest, size 0x7aec4 lma 0x87801320
Loading section .rodata, size 0x16f42 lma 0x8787c1e8
Loading section .hash, size 0x18 lma 0x8789312c
Loading section .data, size 0x7bf4 lma 0x87893148
Loading section .got.plt, size 0xc lma 0x8789ad3c
Loading section .u_boot_list, size 0x126c lma 0x8789ad48
Loading section .efi_runtime_rel, size 0xd0 lma 0x8789bfb4
Loading section .rel.dyn, size 0x10198 lma 0x8789c084
Loading section .dynsym, size 0x30 lma 0x878ac21c
Loading section .dynstr, size 0x1 lma 0x878ac24c
Loading section .dynamic, size 0x90 lma 0x878ac250
Loading section .gnu.hash, size 0x18 lma 0x878ac2e0
Start address 0x87800000, load size 705243
Transfer rate: 69 KB/sec, 13060 bytes/write.
(gdb) load
Loading section .text, size 0x3a8 lma 0x87800000
Loading section .efi_runtime, size 0xf68 lma 0x878003a8
Loading section .text_rest, size 0x7aec4 lma 0x87801320
Loading section .rodata, size 0x16f42 lma 0x8787c1e8
Loading section .hash, size 0x18 lma 0x8789312c
Loading section .data, size 0x7bf4 lma 0x87893148
Loading section .got.plt, size 0xc lma 0x8789ad3c
Loading section .u_boot_list, size 0x126c lma 0x8789ad48
Loading section .efi_runtime_rel, size 0xd0 lma 0x8789bfb4
Loading section .rel.dyn, size 0x10198 lma 0x8789c084
Loading section .dynsym, size 0x30 lma 0x878ac21c
Loading section .dynstr, size 0x1 lma 0x878ac24c
Loading section .dynamic, size 0x90 lma 0x878ac250
Loading section .gnu.hash, size 0x18 lma 0x878ac2e0
Start address 0x87800000, load size 705243
Transfer rate: 69 KB/sec, 13060 bytes/write.
3.2. Restore binary device tree by appending u-boot.dtb file at the end of u-boot image:
(gdb) b fdtdec_prepare_fdt
Breakpoint 1 at 0x87870be4: file lib/fdtdec.c, line 587.
(gdb) c
Continuing.
Breakpoint 1, fdtdec_prepare_fdt () at lib/fdtdec.c:587
587 if (!gd->fdt_blob || ((uintptr_t)gd->fdt_blob & 3) ||
(gdb) set gd->fdt_blob = _end
(gdb) restore u-boot.dtb binary _end
Restoring binary file u-boot.dtb into memory (0x878ac21c to 0x878b38bb)
3.3. Handle code relocation:
(gdb) b setup_reloc
Breakpoint 2 at 0x8781a874: file common/board_f.c, line 680.
(gdb) c
Continuing.
Breakpoint 2, setup_reloc () at common/board_f.c:680
680 if (gd->flags & GD_FLG_SKIP_RELOC) {
(gdb) p /x gd->relocaddr
$1 = 0x8ff37000
(gdb) set $s = gd->relocaddr
(gdb) add-symbol-file u-boot $s
add symbol table from file "u-boot" at
.text_addr = 0x8ff37000
Reading symbols from u-boot...
(gdb) b relocate_code
Breakpoint 3 at 0x87801bc4: file arch/arm/lib/relocate.S, line 81.
(gdb) c
Continuing.
Breakpoint 3, relocate_code () at arch/arm/lib/relocate.S:81
81 ldr r1, =__image_copy_start /* r1 <- SRC &__image_copy_start */
(gdb) p /x $pc
$5 = 0x87801bc4
(gdb) fin
Run till exit from #0 relocate_code () at arch/arm/lib/relocate.S:81
?? () at arch/arm/lib/crt0.S:145
145 bl relocate_vectors
(gdb) p /x $pc
$6 = 0x8ff386a8
3.4. Pass till the end to jump to kernel:
(gdb) b boot_jump_linux
Breakpoint 4 at 0x87801cd0: boot_jump_linux. (2 locations)
(gdb) c
Continuing.
Breakpoint 4, boot_jump_linux (images=images@entry=0x8ffd3bcc, flag=flag@entry=1024) at arch/arm/lib/bootm.c:378
378 unsigned long machid = gd->bd->bi_arch_number;
(gdb) n
384 kernel_entry = (void (*)(int, int, uint))images->ep;
(gdb) n
389 s = env_get("machid");
(gdb) n
390 if (s) {
(gdb) n
400 bootstage_mark(BOOTSTAGE_ID_RUN_OS);
(gdb) n
401 announce_and_cleanup(fake);
(gdb) n
403 if (IMAGE_ENABLE_OF_LIBFDT && images->ft_len)
(gdb) n
404 r2 = (unsigned long)images->ft_addr;
(gdb) n
406 r2 = gd->bd->bi_boot_params;
(gdb) n
408 if (!fake) {
(gdb) n
416 kernel_entry(0, machid, r2);
To start debugging press Run --> Debug Configurations, select u-boot Default configuration.
Pay attention for following settings:
Then press Debug:
Eclipse suggests to swith to Debug perspective - accept it. Wait few seconds before image to be uploaded to hardware:
Don't mind about no debug information available message, just press to Resume (F8) button:
and navigate through the code. If you left breakpoint unchanged it should stop you at relocate_code function. So to pass relocation successfully you should manually place u-boot image at relocation address. For that open Debugger Console and type commands explained before:
Than you can continue to debug code even after relocation.
First, power up device and press enter on u-boot countdown to prevent linux kernel loading.
- Enter Linux kernel sources folder:
cd /opt/eclipse/imx6ull-openwrt/build_dir/target-arm_cortex-a7+neon-vfpv4_musl_eabi/linux-imx6ull_cortexa7/linux-5.4.168/
- make sure that debugging optimized build option selected in
.configfile:
$ cat .config | grep OPTIMIZE
CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE=y
# CONFIG_CC_OPTIMIZE_FOR_SIZE is not set
# CONFIG_CC_OPTIMIZE_FOR_DEBUGGING is not set
- build kernel image:
make -j $(nproc) uImage LOADADDR=0x80008000
- start GDB server:
$ jl_server
SEGGER J-Link GDB Server V7.54b Command Line Version
JLinkARM.dll V7.54b (DLL compiled Sep 14 2021 16:11:24)
Command line: -device MCIMX6Y2 -if JTAG -speed 1000
-----GDB Server start settings-----
GDBInit file: none
GDB Server Listening port: 2331
SWO raw output listening port: 2332
Terminal I/O port: 2333
Accept remote connection: yes
Generate logfile: off
Verify download: off
Init regs on start: off
Silent mode: off
Single run mode: off
Target connection timeout: 0 ms
------J-Link related settings------
J-Link Host interface: USB
J-Link script: none
J-Link settings file: none
------Target related settings------
Target device: MCIMX6Y2
Target interface: JTAG
Target interface speed: 1000kHz
Target endian: little
Connecting to J-Link...
J-Link is connected.
Firmware: J-Link ARM V8 compiled Nov 28 2014 13:44:46
Hardware: V8.00
Feature(s): RDI,FlashDL,FlashBP,JFlash,GDB
Checking target voltage...
Target voltage: 3.32 V
Listening on TCP/IP port 2331
Connecting to target...
J-Link found 3 JTAG devices, Total IRLen = 13
JTAG ID: 0x5BA00477 (Cortex-A7)
Connected to target
- start GDB session (from another shell):
$ jl_kernel
GNU gdb (Ubuntu 10.1-2ubuntu2) 10.1.90.20210411-git
Reading symbols from vmlinux...
(gdb)
and connect to target hardware:
(gdb) target remote localhost:2331
Remote debugging using localhost:2331
0x8ff5cfc4 in ?? ()
- load binary
uImagecompiled on step 3 and binarydtbfile compiled previously on running.setup_ide.sh:
(gdb) restore arch/arm/boot/uImage binary 0x82000000
Restoring binary file arch/arm/boot/uImage into memory (0x82000000 to 0x8241c758)
(gdb) restore ../image-flexcan_ethernet.dtb binary 0x83000000
Restoring binary file ../image-flexcan_ethernet.dtb into memory (0x83000000 to 0x83006b47)
- set breakpoint on kernel starting function and start processor running:
(gdb) b __hyp_stub_install
Breakpoint 1 at 0x8010fb80: file arch/arm/kernel/hyp-stub.S, line 76.
(gdb) c
Continuing.
- ater that u-boot shell should become back responcible for typing. Start kernel booting by:
=> bootm 82000000 - 83000000
## Booting kernel from Legacy Image at 82000000 ...
Image Name: Linux-5.4.168
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 4310808 Bytes = 4.1 MiB
Load Address: 80008000
Entry Point: 80008000
Verifying Checksum ... OK
## Flattened Device Tree blob at 83000000
Booting using the fdt blob at 0x83000000
Loading Kernel Image ... OK
Using Device Tree in place at 83000000, end 83009b46
Starting kernel ...
- Switch back to gdb shell - it should stop on breakpoint:
Continuing.
Breakpoint 1, __hyp_stub_install () at arch/arm/kernel/hyp-stub.S:76
76 store_primary_cpu_mode r4, r5, r6
(gdb)
set breakpoint to start_kernel function and start processor running again:
(gdb) b start_kernel
Breakpoint 2 at 0x80a00934: file init/main.c, line 605.
(gdb) c
Continuing.
Breakpoint 2, start_kernel () at init/main.c:605
605 set_task_stack_end_magic(&init_task);
and walk through the code:
(gdb) n
606 smp_setup_processor_id();
(gdb) n
611 local_irq_disable();
(gdb) n
612 early_boot_irqs_disabled = true;
(gdb) n
624 setup_command_line(command_line);
(gdb) n
618 boot_cpu_init();
(gdb) n
619 page_address_init();
(gdb) n
620 pr_notice("%s", linux_banner);
(gdb) p /s linux_banner
$6 = 0x808aad94 <linux_banner> "Linux version 5.4.168 (al@b94678055031) (gcc version 8.4.0 (OpenWrt GCC 8.4.0 r16520-531aad5aa0)) #2 SMP PREEMPT Sun Jan 23 18:24:31 MSK 2022\n"
(gdb) n
624 setup_command_line(command_line);
(gdb) n
622 setup_arch(&command_line);
(gdb) n
624 setup_command_line(command_line);
(gdb) p /s command_line
$9 = 0x80a42a58 <cmd_line> "console=ttymxc0,115200 rootwait fixrtc quiet"
(gdb) n
625 setup_nr_cpu_ids();
(gdb) n
626 setup_per_cpu_areas();
(gdb) n
627 smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
(gdb) n
628 boot_cpu_hotplug_init();
(gdb) n
630 build_all_zonelists(NULL);
(gdb) n
631 page_alloc_init();
(gdb) n
633 pr_notice("Kernel command line: %s\n", boot_command_line);
(gdb) p /s boot_command_line
$11 = 0x80a42004 <boot_command_line> "console=ttymxc0,115200 rootwait fixrtc quiet"
(gdb) n
635 jump_label_init();
(gdb) n
636 parse_early_param();
(gdb) n
637 after_dashes = parse_args("Booting kernel",
(gdb) n
641 if (!IS_ERR_OR_NULL(after_dashes))
(gdb) n
649 setup_log_buf(0);
(gdb) n
653 mm_init();
(gdb) n
651 sort_main_extable();
(gdb) n
652 trap_init();
(gdb) n
653 mm_init();
(gdb) n
665 sched_init();
(gdb) n
670 preempt_disable();
(gdb) n
671 if (WARN(!irqs_disabled(),
(gdb) n
674 radix_tree_init();
(gdb) n
680 housekeeping_init();
(gdb) n
687 workqueue_init_early();
(gdb) n
689 rcu_init();
(gdb) n
699 early_irq_init();
(gdb) n
700 init_IRQ();
(gdb) n
701 tick_init();
(gdb) n
703 init_timers();
(gdb) n
704 hrtimers_init();
(gdb) n
705 softirq_init();
(gdb) n
706 timekeeping_init();
(gdb) n
716 rand_initialize();
(gdb) n
718 add_device_randomness(command_line, strlen(command_line));
(gdb) n
719 boot_init_stack_canary();
(gdb) n
721 time_init();
(gdb) n
724 call_function_init();
(gdb) n
725 WARN(!irqs_disabled(), "Interrupts were enabled early\n");
(gdb) n
727 early_boot_irqs_disabled = false;
(gdb) n
728 local_irq_enable();
(gdb) n
730 kmem_cache_init_late();
(gdb) n
737 console_init();
(gdb) n
738 if (panic_later)
(gdb) n
757 mem_encrypt_init();
(gdb) n
760 if (initrd_start && !initrd_below_start_ok &&
(gdb) n
768 setup_per_cpu_pageset();
(gdb) n
771 if (late_time_init)
(gdb) n
773 sched_clock_init();
(gdb) n
774 calibrate_delay();
(gdb) n
775 pid_idr_init();
(gdb) n
776 anon_vma_init();
(gdb) n
781 thread_stack_cache_init();
(gdb) n
782 cred_init();
(gdb) n
783 fork_init();
(gdb) n
784 proc_caches_init();
(gdb) n
786 buffer_init();
(gdb) n
787 key_init();
(gdb) n
790 vfs_caches_init();
(gdb) n
791 pagecache_init();
(gdb) n
792 signals_init();
(gdb) n
793 seq_file_init();
(gdb) n
794 proc_root_init();
(gdb) n
795 nsfs_init();
(gdb) n
801 poking_init();
(gdb) n
802 check_bugs();
(gdb) n
805 arch_post_acpi_subsys_init();
(gdb) n
809 arch_call_rest_init();
(gdb) n
-
Power up device connected to JLink debugger and USB-UART adapter. Press on u-boot countdown to prevent kernel loading.
-
Connect to IDE container and start GDB server: Don't provide executable file here.
$ docker exec -it openwrt bash
$ jl_server
SEGGER J-Link GDB Server V7.54b Command Line Version
JLinkARM.dll V7.54b (DLL compiled Sep 14 2021 16:11:24)
Command line: -device MCIMX6Y2 -if JTAG -speed 1000
-----GDB Server start settings-----
GDBInit file: none
GDB Server Listening port: 2331
SWO raw output listening port: 2332
Terminal I/O port: 2333
Accept remote connection: yes
Generate logfile: off
Verify download: off
Init regs on start: off
Silent mode: off
Single run mode: off
Target connection timeout: 0 ms
------J-Link related settings------
J-Link Host interface: USB
J-Link script: none
J-Link settings file: none
------Target related settings------
Target device: MCIMX6Y2
Target interface: JTAG
Target interface speed: 1000kHz
Target endian: little
Connecting to J-Link...
J-Link is connected.
Firmware: J-Link ARM V8 compiled Nov 28 2014 13:44:46
Hardware: V8.00
Feature(s): RDI,FlashDL,FlashBP,JFlash,GDB
Checking target voltage...
Target voltage: 3.31 V
Listening on TCP/IP port 2331
Connecting to target...
J-Link found 3 JTAG devices, Total IRLen = 13
JTAG ID: 0x5BA00477 (Cortex-A7)
Connected to target
Waiting for GDB connection...
- Connect to IDE container from another shell:
$ docker exec -it openwrt bash
- Enter sources root folder and start gdb session:
$ cd /opt/eclipse/imx6ull-openwrt
$ gdb-multiarch --nx
For help, type "help".
Type "apropos word" to search for commands related to "word".
(gdb)
- Connect to target and provide u-boot debuggable executable:
(gdb) set confirm off
(gdb) file build_dir/target-arm_cortex-a7+neon-vfpv4_musl_eabi/u-boot-wirelessroad_ecspi3/u-boot-2020.10/u-boot
Reading symbols from build_dir/target-arm_cortex-a7+neon-vfpv4_musl_eabi/u-boot-wirelessroad_ecspi3/u-boot-2020.10/u-boot...
(gdb) target remote localhost:2331
Remote debugging using localhost:2331
Cannot access memory at address 0xc93c4
Cannot access memory at address 0xc93c0
Cannot access memory at address 0xc93c4
0x8ff5cfc4 in ?? ()
(gdb) monitor reset
Resetting target
(gdb) monitor halt
(gdb) monitor sleep 200
Sleep 200ms
- Load u-boot executable twice (loading it just once leads to unstable debugging process):
(gdb) load
Loading section .text, size 0x3a8 lma 0x87800000
Loading section .efi_runtime, size 0xf68 lma 0x878003a8
Loading section .text_rest, size 0x7aec4 lma 0x87801320
Loading section .rodata, size 0x16f42 lma 0x8787c1e8
Loading section .hash, size 0x18 lma 0x8789312c
Loading section .data, size 0x7bf4 lma 0x87893148
Loading section .got.plt, size 0xc lma 0x8789ad3c
Loading section .u_boot_list, size 0x126c lma 0x8789ad48
Loading section .efi_runtime_rel, size 0xd0 lma 0x8789bfb4
Loading section .rel.dyn, size 0x10198 lma 0x8789c084
Loading section .dynsym, size 0x30 lma 0x878ac21c
Loading section .dynstr, size 0x1 lma 0x878ac24c
Loading section .dynamic, size 0x90 lma 0x878ac250
Loading section .gnu.hash, size 0x18 lma 0x878ac2e0
Start address 0x87800000, load size 705243
Transfer rate: 69 KB/sec, 13060 bytes/write.
(gdb) load
Loading section .text, size 0x3a8 lma 0x87800000
Loading section .efi_runtime, size 0xf68 lma 0x878003a8
Loading section .text_rest, size 0x7aec4 lma 0x87801320
Loading section .rodata, size 0x16f42 lma 0x8787c1e8
Loading section .hash, size 0x18 lma 0x8789312c
Loading section .data, size 0x7bf4 lma 0x87893148
Loading section .got.plt, size 0xc lma 0x8789ad3c
Loading section .u_boot_list, size 0x126c lma 0x8789ad48
Loading section .efi_runtime_rel, size 0xd0 lma 0x8789bfb4
Loading section .rel.dyn, size 0x10198 lma 0x8789c084
Loading section .dynsym, size 0x30 lma 0x878ac21c
Loading section .dynstr, size 0x1 lma 0x878ac24c
Loading section .dynamic, size 0x90 lma 0x878ac250
Loading section .gnu.hash, size 0x18 lma 0x878ac2e0
Start address 0x87800000, load size 705243
Transfer rate: 69 KB/sec, 13060 bytes/write.
- Start execution and place u-boot dtb in memory:
(gdb) b fdtdec_prepare_fdt
Breakpoint 1 at 0x87870be4: file lib/fdtdec.c, line 587.
(gdb) c
Continuing.
Breakpoint 1, fdtdec_prepare_fdt () at lib/fdtdec.c:587
587 if (!gd->fdt_blob || ((uintptr_t)gd->fdt_blob & 3) ||
(gdb) set gd->fdt_blob = _end
(gdb) restore build_dir/target-arm_cortex-a7+neon-vfpv4_musl_eabi/u-boot-wirelessroad_ecspi3/u-boot-2020.10/u-boot.dtb binary _end
Restoring binary file build_dir/target-arm_cortex-a7+neon-vfpv4_musl_eabi/u-boot-wirelessroad_ecspi3/u-boot-2020.10/u-boot.dtb into memory (0x878ac21c to 0x878b38bb)
- Pass U-boot relocation procedure:
(gdb) b setup_reloc
Breakpoint 2 at 0x8781a874: file common/board_f.c, line 680.
(gdb) c
Continuing.
Breakpoint 2, setup_reloc () at common/board_f.c:680
680 if (gd->flags & GD_FLG_SKIP_RELOC) {
(gdb) p /x gd->relocaddr
$1 = 0x8ff37000
(gdb) set $s = gd->relocaddr
(gdb) add-symbol-file build_dir/target-arm_cortex-a7+neon-vfpv4_musl_eabi/u-boot-wirelessroad_ecspi3/u-boot-2020.10/u-boot $s
add symbol table from file "build_dir/target-arm_cortex-a7+neon-vfpv4_musl_eabi/u-boot-wirelessroad_ecspi3/u-boot-2020.10/u-boot" at
.text_addr = 0x8ff37000
Reading symbols from build_dir/target-arm_cortex-a7+neon-vfpv4_musl_eabi/u-boot-wirelessroad_ecspi3/u-boot-2020.10/u-boot...
(gdb) b relocate_code
Breakpoint 3 at 0x87801bc4: file arch/arm/lib/relocate.S, line 81.
(gdb) c
Continuing.
Breakpoint 3, relocate_code () at arch/arm/lib/relocate.S:81
81 ldr r1, =__image_copy_start /* r1 <- SRC &__image_copy_start */
(gdb) p /x $pc
$2 = 0x87801bc4
(gdb) fin
Run till exit from #0 relocate_code () at arch/arm/lib/relocate.S:81
?? () at arch/arm/lib/crt0.S:145
145 bl relocate_vectors
(gdb) p /x $pc
$3 = 0x8ff386a8
- Run forward till jumping to Linux Kernel:
(gdb) b boot_jump_linux
Breakpoint 4 at 0x87801cd0: boot_jump_linux. (2 locations)
(gdb) c
Continuing.
Breakpoint 4, boot_jump_linux (images=images@entry=0x8ffd3bcc, flag=flag@entry=1024) at arch/arm/lib/bootm.c:378
378 unsigned long machid = gd->bd->bi_arch_number;
(gdb) n
384 kernel_entry = (void (*)(int, int, uint))images->ep;
(gdb) n
389 s = env_get("machid");
(gdb) p /x kernel_entry
$4 = 0x80008000
(gdb) n
390 if (s) {
(gdb) n
400 bootstage_mark(BOOTSTAGE_ID_RUN_OS);
(gdb) n
401 announce_and_cleanup(fake);
(gdb) n
403 if (IMAGE_ENABLE_OF_LIBFDT && images->ft_len)
(gdb) n
404 r2 = (unsigned long)images->ft_addr;
(gdb) n
406 r2 = gd->bd->bi_boot_params;
(gdb) n
408 if (!fake) {
(gdb) n
416 kernel_entry(0, machid, r2);
(gdb) p /x $r2
$5 = 0x80000100
- Then load linux kernel executable:
(gdb) file build_dir/target-arm_cortex-a7+neon-vfpv4_musl_eabi/linux-imx6ull_cortexa7/linux-5.4.168/vmlinux
Reading symbols from build_dir/target-arm_cortex-a7+neon-vfpv4_musl_eabi/linux-imx6ull_cortexa7/linux-5.4.168/vmlinux...
(gdb) load
Loading section .head.text, size 0x26c lma 0x80008000
Loading section .text, size 0x6062b8 lma 0x80100000
Loading section .rodata, size 0x17fab8 lma 0x80800000
Loading section .pci_fixup, size 0x1ef0 lma 0x8097fab8
Loading section __ksymtab, size 0xcaec lma 0x809819a8
Loading section __ksymtab_gpl, size 0xbd54 lma 0x8098e494
Loading section __ksymtab_strings, size 0x27eb3 lma 0x8099a1e8
Loading section __param, size 0xd98 lma 0x809c209c
Loading section __ex_table, size 0x660 lma 0x809c3000
Loading section .ARM.unwind_idx, size 0x29d98 lma 0x809c3660
Loading section .ARM.unwind_tab, size 0x924 lma 0x809ed3f8
Loading section .notes, size 0x3c lma 0x809edd1c
Loading section .vectors, size 0x20 lma 0x80a00000
Loading section .stubs, size 0x2ac lma 0x80a00020
Loading section .init.text, size 0x3b40c lma 0x80a002e0
Loading section .exit.text, size 0x11fc lma 0x80a3b6ec
Loading section .init.arch.info, size 0x208 lma 0x80a3c8e8
Loading section .init.tagtable, size 0x40 lma 0x80a3caf0
Loading section .init.smpalt, size 0x4d80 lma 0x80a3cb30
Loading section .init.pv_table, size 0x17c lma 0x80a418b0
Loading section .init.data, size 0xdd4c lma 0x80a42000
Loading section .data..percpu, size 0x6d0c lma 0x80a50000
Loading section .data, size 0x3fe00 lma 0x80b00000
Loading section __bug_table, size 0x5298 lma 0x80b3fe00
Start address 0x80008000, load size 8975799
Transfer rate: 70 KB/sec, 15802 bytes/write.
(gdb) load
Loading section .head.text, size 0x26c lma 0x80008000
Loading section .text, size 0x6062b8 lma 0x80100000
Loading section .rodata, size 0x17fab8 lma 0x80800000
Loading section .pci_fixup, size 0x1ef0 lma 0x8097fab8
Loading section __ksymtab, size 0xcaec lma 0x809819a8
Loading section __ksymtab_gpl, size 0xbd54 lma 0x8098e494
Loading section __ksymtab_strings, size 0x27eb3 lma 0x8099a1e8
Loading section __param, size 0xd98 lma 0x809c209c
Loading section __ex_table, size 0x660 lma 0x809c3000
Loading section .ARM.unwind_idx, size 0x29d98 lma 0x809c3660
Loading section .ARM.unwind_tab, size 0x924 lma 0x809ed3f8
Loading section .notes, size 0x3c lma 0x809edd1c
Loading section .vectors, size 0x20 lma 0x80a00000
Loading section .stubs, size 0x2ac lma 0x80a00020
Loading section .init.text, size 0x3b40c lma 0x80a002e0
Loading section .exit.text, size 0x11fc lma 0x80a3b6ec
Loading section .init.arch.info, size 0x208 lma 0x80a3c8e8
Loading section .init.tagtable, size 0x40 lma 0x80a3caf0
Loading section .init.smpalt, size 0x4d80 lma 0x80a3cb30
Loading section .init.pv_table, size 0x17c lma 0x80a418b0
Loading section .init.data, size 0xdd4c lma 0x80a42000
Loading section .data..percpu, size 0x6d0c lma 0x80a50000
Loading section .data, size 0x3fe00 lma 0x80b00000
Loading section __bug_table, size 0x5298 lma 0x80b3fe00
Start address 0x80008000, load size 8975799
Transfer rate: 69 KB/sec, 15802 bytes/write.
- Remove U-boot breakpoints:
(gdb) del
- Run Linux kernel and enter start_kernel function:
(gdb) b start_kernel
Breakpoint 5 at 0x80a00934: file init/main.c, line 605.
(gdb) restore build_dir/target-arm_cortex-a7+neon-vfpv4_musl_eabi/linux-imx6ull_cortexa7/image-flexcan_ethernet.dtb binary 0x83000000
Restoring binary file build_dir/target-arm_cortex-a7+neon-vfpv4_musl_eabi/linux-imx6ull_cortexa7/image-flexcan_ethernet.dtb into memory (0x83000000 to 0x83006b47)
(gdb) set $r2=0x83000000
(gdb) c
Continuing.
Breakpoint 5, start_kernel () at init/main.c:605
605 set_task_stack_end_magic(&init_task);
- Walk through initialization procedure:
(gdb) n
606 smp_setup_processor_id();
(gdb) n
611 local_irq_disable();
(gdb) n
612 early_boot_irqs_disabled = true;
(gdb) n
624 setup_command_line(command_line);
(gdb) n
618 boot_cpu_init();
(gdb) n
619 page_address_init();
(gdb) n
620 pr_notice("%s", linux_banner);
(gdb) n
624 setup_command_line(command_line);
(gdb) p /s linux_banner
$6 = 0x808aad94 <linux_banner> "Linux version 5.4.168 (al@b94678055031) (gcc version 8.4.0 (OpenWrt GCC 8.4.0 r16520-531aad5aa0)) #2 SMP PREEMPT Sun Jan 23 18:24:31 MSK 2022\n"
(gdb) n
622 setup_arch(&command_line);
(gdb) n
624 setup_command_line(command_line);
(gdb) p /s command_line
$7 = 0x80a42a58 <cmd_line> "console=ttymxc0,115200 rootwait fixrtc quiet"
to exit docker container:
$ exit
to enter it back:
$ docker start openwrt
$ docker exec -it openwrt bash
here two developers guide to develop and debug user layer applications:
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