Hi Kieran,
Thanks for reviewing.
On Tue, 18 Oct 2016, Kieran Bingham wrote:
> Hi Pete,
>
> Thanks for your patch.
>
> On 18/10/16 16:07, Peter Griffin wrote:
> > lx-fdtdump dumps the flatenned device tree passed to the kernel
>
> s/flatenned/flattened/
>
> > 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:
> >
>
> Excellent - I've been looking forward to this
>
> General comment: It would be good to see the output filename
> configurable as a parameter, defaulting to fdtdump.dtb if none provided.
>
> Is this something you have time to add?
Have added this in v2 :)
>
> > (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"
> > +
>
> You could parse the arguments here to allow users to write to their own
> file / path ... arg is just a string, so you can either parse it as such
> or convert to argv with
> argv = gdb.string_to_argv(arg)
>
>
> Aha - I see Jan beat me to it :)
>
>
> > + py_fdt_header_ptr = gdb.parse_and_eval(
> > + "(const struct fdt_header *) initial_boot_params")
> > + py_fdt_header = py_fdt_header_ptr.dereference()
> > +
> > + fdt_header = self.fdthdr_to_cpu(py_fdt_header)
> > +
> > + if fdt_header[0] != constants.LX_OF_DT_HEADER:
> > + raise gdb.GdbError("No flattened device tree magic found\n")
> > +
> > + gdb.write("fdt_magic: 0x{:02X}\n".format(fdt_header[0]))
> > + gdb.write("fdt_totalsize: 0x{:02X}\n".format(fdt_header[1]))
> > + gdb.write("off_dt_struct: 0x{:02X}\n".format(fdt_header[2]))
> > + gdb.write("off_dt_strings: 0x{:02X}\n".format(fdt_header[3]))
> > + gdb.write("off_mem_rsvmap: 0x{:02X}\n".format(fdt_header[4]))
> > + gdb.write("version: {}\n".format(fdt_header[5]))
> > + gdb.write("last_comp_version: {}\n".format(fdt_header[6]))
> > +
> > + inf = gdb.inferiors()[0]
> > + fdt_buf = utils.read_memoryview(inf, py_fdt_header_ptr,
> > + fdt_header[1]).tobytes()
> > +
> > + try:
> > + f = open(filename, 'wb')
> > + except:
> > + raise gdb.GdbError("Could not open file to dump fdt")
> > +
> > + f.write(fdt_buf)
> > + f.close()
> > +
> > + gdb.write("Dumped fdt to " + filename + "\n")
> > +
> > + else:
> > + gdb.write("Kernel not compiled with CONFIG_OF\n")
>
> Would it be cleaner to write
> if not constants.LX_CONFIG_OF:
> raise gdb.GdbError("Kernel not compiled with CONFIG_OF\n")
>
> at the beginning, and reduce the indentation level required ?
Good idea, have updated like you suggest in V2 and reduced the
indentation.
regards,
Peter
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