-Prabhu
On Thu, May 19, 2011 at 6:45 AM, Dongdong Deng <libfetion@xxxxxxxxx> wrote:
On Wed, May 18, 2011 at 7:23 PM, Prabhu nath <gprabhunath@xxxxxxxxx> wrote:Hi Prabhu,
> Dear All,
>
> There is a problem with the KGDB at the very first break point after
> executing the gdb command "target remote /dev/ttyS0" from the host.
> I have verbatim, followed the KGDB document
> http://kernel.org/pub/linux/kernel/people/jwessel/kdb/
>
> Problem Logs:
> ---------------------
>
> Details of my hardware and system software:
> -------------------------------------------------------------------
>
> *Host (Development machine): *
> Intel Pentium IV Machine with Fedora Core 12
> Linux Version : 2.6.31.5-127.fc12.i686.PAE
> gdb version : GNU gdb (GDB) Fedora (7.0-3.fc12)
>
> *Target:*
> Intel Pentium IV Machine with Fedora Core 12
> Customized Linux Version : 2.6.38
>
> Host is connected to Target via a null modem cable
>
> *Snapshot of .config of linux version 2.6.38 on the target *
> *
> *
> # CONFIG_DEBUG_RODATA is not set
The CONFIG_DEBUG_RODATA was suggested to set at KGDB,
Could you enable it?
CONFIG_DEBUG_RODATA = y
Dongdong
>
> CONFIG_HAVE_ARCH_KGDB=y
> CONFIG_FRAME_POINTER=y
> CONFIG_DEBUG_INFO=y
> CONFIG_KGDB=y
> CONFIG_KGDB_SERIAL_CONSOLE=y
> CONFIG_KGDB_LOW_LEVEL_TRAP=y
>
> *Grub config on the target machine*
> *
> *
> title Fedora (2.6.38)
> root (hd0,0)
> kernel /boot/vmlinuz-2.6.38 ro
> root=UUID=fb7800fb-cfe7-438d-bc7f-c153ba4353d1 LANG=en_US.UTF-8
> SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=us*console=ttyS0,115200n8> kgdboc=ttyS0 kgdbwai*t
> ------------------------------------------------------------------------------> initrd /boot/initrd-2.6.38.img
>
>
> On power on of the target, linux kernel boots and the logs are seen on the
> minicom console of the host and it will wait for the gdb on the host to
> connect. Here is the last 4 lines of the logs seen on the minicom
>
> Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
> serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
> 00:06: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
> kgdb: Registered I/O driver kgdboc.
> kgdb: Waiting for connection from remote gdb..
>
> *--- Now I close the minicom console (Ctrl-A X) and start the gdb on the
> host. Here is the steps I follow. *
> *
> *
> *On the host machine:*
> *
> *
>
> [root@localhost kgdb]# gdb vmlinux
>
> GNU gdb (GDB) Fedora (7.0-3.fc12)
> Copyright (C) 2009 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html
>>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law. Type "show copying"
> and "show warranty" for details.
> This GDB was configured as "i686-redhat-linux-gnu".
> For bug reporting instructions, please see:
> <http://www.gnu.org/software/gdb/bugs/>...
> Reading symbols from /root/kgdb/vmlinux...done.
>
> (gdb) set remotebaud 115200
> (gdb) set debug remote 1
> (gdb) target remote /dev/ttyS0
> Remote debugging using /dev/ttyS0
> Sending packet: $qSupported#37...Ack
> Packet received:
> Packet qSupported (supported-packets) is NOT supported
> Sending packet: $Hg0#df...Ack
> Packet received: OK
> Sending packet: $?#3f...Ack
> Packet received: S05
> Sending packet: $Hc-1#09...Ack
> Packet received: OK
> Sending packet: $qC#b4...Ack
> Packet received: QC01
> Sending packet: $qAttached#8f...Ack
> Packet received:
> Packet qAttached (query-attached) is NOT supported
> Sending packet: $qOffsets#4b...Ack
> Packet received:
> Sending packet: $g#67...Ack
> Packet received:
> 36000000ffffffff0abaffff20d98bc06c3f86de783f86de803ac8dd803f86de885747c00202000060000000680000007b00c8dd7b0086deffff0000ffff0000
> Sending packet: $mc0475788,1#a4...Ack
> Packet received: 0f
> Sending packet: $mc0475788,8#ab...Ack
> Packet received: 0faef889f6ff0d08
> Sending packet: $mc0475788,7#aa...Ack
> Packet received: 0faef889f6ff0d
> 0xc0475788 in ?? ()
> Sending packet: $qSymbol::#5b...Ack
> Packet received:
> Packet qSymbol (symbol-lookup) is NOT supported
> (gdb) s
> Cannot find bounds of current function
> (gdb)
>
>
> *Observation:*
> *1.* Ideally the kernel being debugged should break at
> legitimate address and the corresponding line number should
> be displayed instead of " 0xc0475788 in ?? ()".
>
> 2. On inspecting section header in vmlinux executable,
> I found the .text section address range is from
> 0xC1000000 to 0xC1326e58 and no section's contents
> associate with the address 0xC0475788.
>
> *3.* Hence on single stepping, gdb logs the error
> as* "Cannot
> find bounds of current function"*
> *
> *
> Humbly request you to help me in addressing this issue.
>
> Thanks and Regards,
> Prabhu
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