On 2016-10-18 18:06, Peter Griffin wrote:
> Hi Jan,
>
> On Tue, 18 Oct 2016, Jan Kiszka wrote:
>
>> On 2016-10-18 17:07, Peter Griffin wrote:
>>> lx-fdtdump dumps the flatenned device tree passed to the kernel
>>> from the bootloader to a file called fdtdump.dtb to allow further
>>> post processing on the machine running GDB. The fdt header is also
>>> also printed in the GDB console. For example:
>>>
>>> (gdb) lx-fdtdump
>>> fdt_magic: 0xD00DFEED
>>> fdt_totalsize: 0xC108
>>> off_dt_struct: 0x38
>>> off_dt_strings: 0x3804
>>> off_mem_rsvmap: 0x28
>>> version: 17
>>> last_comp_version: 16
>>> Dumped fdt to fdtdump.dtb
>>>
>>>> fdtdump fdtdump.dtb | less
>>>
>>> This command is useful as the bootloader can often re-write parts
>>> of the device tree, and this can sometimes cause the kernel to not
>>> boot.
>>>
>>> Signed-off-by: Peter Griffin <peter.griffin@xxxxxxxxxx>
>>> ---
>>> scripts/gdb/linux/constants.py.in | 8 +++++
>>> scripts/gdb/linux/proc.py | 70 ++++++++++++++++++++++++++++++++++++++-
>>> 2 files changed, 77 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/scripts/gdb/linux/constants.py.in b/scripts/gdb/linux/constants.py.in
>>> index 7986f4e..43c6241 100644
>>> --- a/scripts/gdb/linux/constants.py.in
>>> +++ b/scripts/gdb/linux/constants.py.in
>>> @@ -14,6 +14,7 @@
>>>
>>> #include <linux/fs.h>
>>> #include <linux/mount.h>
>>> +#include <linux/of_fdt.h>
>>>
>>> /* We need to stringify expanded macros so that they can be parsed */
>>>
>>> @@ -50,3 +51,10 @@ LX_VALUE(MNT_NOEXEC)
>>> LX_VALUE(MNT_NOATIME)
>>> LX_VALUE(MNT_NODIRATIME)
>>> LX_VALUE(MNT_RELATIME)
>>> +
>>> +/* linux/of_fdt.h> */
>>> +LX_VALUE(OF_DT_HEADER)
>>> +
>>> +/* Kernel Configs */
>>> +LX_CONFIG(CONFIG_OF)
>>> +
>>> diff --git a/scripts/gdb/linux/proc.py b/scripts/gdb/linux/proc.py
>>> index 38b1f09..f20fcfa 100644
>>> --- a/scripts/gdb/linux/proc.py
>>> +++ b/scripts/gdb/linux/proc.py
>>> @@ -16,7 +16,7 @@ from linux import constants
>>> from linux import utils
>>> from linux import tasks
>>> from linux import lists
>>> -
>>> +from struct import *
>>>
>>> class LxCmdLine(gdb.Command):
>>> """ Report the Linux Commandline used in the current kernel.
>>> @@ -195,3 +195,71 @@ values of that process namespace"""
>>> info_opts(MNT_INFO, m_flags)))
>>>
>>> LxMounts()
>>> +
>>> +class LxFdtDump(gdb.Command):
>>> + """Output Flattened Device Tree header and dump FDT blob to a file
>>> + Equivalent to 'cat /proc/fdt > fdtdump.dtb' on a running target"""
>>> +
>>> + def __init__(self):
>>> + super(LxFdtDump, self).__init__("lx-fdtdump", gdb.COMMAND_DATA)
>>> +
>>> + def fdthdr_to_cpu(self, fdt_header):
>>> +
>>> + fdt_header_be = ">IIIIIII"
>>> + fdt_header_le = "<IIIIIII"
>>> +
>>> + if utils.get_target_endianness() == 1:
>>> + output_fmt = fdt_header_le
>>> + else:
>>> + output_fmt = fdt_header_be
>>> +
>>> + return unpack(output_fmt, pack(fdt_header_be,
>>> + fdt_header['magic'],
>>> + fdt_header['totalsize'],
>>> + fdt_header['off_dt_struct'],
>>> + fdt_header['off_dt_strings'],
>>> + fdt_header['off_mem_rsvmap'],
>>> + fdt_header['version'],
>>> + fdt_header['last_comp_version']))
>>> +
>>> + def invoke(self, arg, from_tty):
>>> +
>>> + if constants.LX_CONFIG_OF:
>>> +
>>> + filename = "fdtdump.dtb"
>>
>> Why not specifying the file name as argument? Safer than silently
>> overwriting potentially pre-existing files or failing without
>> alternatives if the current directory is not writable.
>
> Good idea, I will update to have the filename as the command argument in v2.
>
Also check gdb.COMPLETE_FILENAME [1] at that chance. :)
Jan
[1]
https://sourceware.org/gdb/onlinedocs/gdb/Commands-In-Python.html#Commands-In-Python
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Corporate Competence Center Embedded Linux
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