ESP32 JTAG

1 Overview

$ sudo apt-get install libftdi-dev make libtool pkg-config autoconf automake texinfo
$ git clone --recursive git://github.com/espressif/openocd-esp32.git
$ cd openocd-esp32
$ ./bootstrap
$ make && sudo make install

3 GDB Tips

3.1 Display Register

(gdb) i r
(gdb) i r a                     # show all registers including float and multimedia
(gdb) i r esp
(gdb) i r pc

3.2 Display Memory

(gdb) x /wx 400801c3     # Display the data at the specified address in hexadecimal
(gdb) x /8x $esp
(gdb) x /16x $esp+12
(gdb) x /16s 0x86468700    # Display the data at the specified address as a string
(gdb) x /24i 0x8048a51     # Display the data at the specified address as instruction (24 instructions)

3.3 Modify Register

(gdb) set $v0 = 0x004000000
(gdb) set $epc = 0xbfc00000

3.4 Modify Memory

(gdb) set {unsigned int}0x8048a51=0x0
(gdb) set *(unsigned int*)0x8048a54=0x55aa55aa

3.5 Search Memory

Usage: find <start> <end> <count> <value>

(gdb) define find                            
set $ptr = $arg0
set $cnt = 0
while ( ($ptr<=$arg1) && ($cnt<$arg2) )
    if ( *(unsigned int *)$ptr == $arg3 )
        x /wx $ptr
        set $cnt = $cnt + 1
    end
    set $ptr = $ptr + 4
end
end

3.6 Breakpoint & Watchpoint

(gdb) b *0x80400000
(gdb) watch *(unsigned int *)0xbffff400==0x90909090