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 <[email protected]>
---
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"
+
+ 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")
+
+LxFdtDump()
--
1.9.1
proc.py:22:1: E302 expected 2 blank lines, found 1
proc.py:200:1: E302 expected 2 blank lines, found 1
Signed-off-by: Peter Griffin <[email protected]>
---
scripts/gdb/linux/proc.py | 2 ++
1 file changed, 2 insertions(+)
diff --git a/scripts/gdb/linux/proc.py b/scripts/gdb/linux/proc.py
index f20fcfa..2d6f74e 100644
--- a/scripts/gdb/linux/proc.py
+++ b/scripts/gdb/linux/proc.py
@@ -18,6 +18,7 @@ from linux import tasks
from linux import lists
from struct import *
+
class LxCmdLine(gdb.Command):
""" Report the Linux Commandline used in the current kernel.
Equivalent to cat /proc/cmdline on a running target"""
@@ -196,6 +197,7 @@ values of that process namespace"""
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"""
--
1.9.1
Hi Pete,
On 18/10/16 16:07, Peter Griffin wrote:
> proc.py:22:1: E302 expected 2 blank lines, found 1
> proc.py:200:1: E302 expected 2 blank lines, found 1
>
> Signed-off-by: Peter Griffin <[email protected]>
> ---
> scripts/gdb/linux/proc.py | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/scripts/gdb/linux/proc.py b/scripts/gdb/linux/proc.py
> index f20fcfa..2d6f74e 100644
> --- a/scripts/gdb/linux/proc.py
> +++ b/scripts/gdb/linux/proc.py
> @@ -18,6 +18,7 @@ from linux import tasks
> from linux import lists
> from struct import *
>
> +
This was added by patch 1, and can be squashed there.
> class LxCmdLine(gdb.Command):
> """ Report the Linux Commandline used in the current kernel.
> Equivalent to cat /proc/cmdline on a running target"""
> @@ -196,6 +197,7 @@ values of that process namespace"""
>
> LxMounts()
>
> +
Likewise...
> 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"""
>
--
Regards
Kieran Bingham
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 <[email protected]>
> ---
> 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.
> +
> + 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")
> +
> +LxFdtDump()
>
Jan
--
Siemens AG, Corporate Technology, CT RDA ITP SES-DE
Corporate Competence Center Embedded Linux
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?
> (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 <[email protected]>
> ---
> 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 ?
> +
> +LxFdtDump()
>
--
Regards
Kieran Bingham
Hi Kieran,
On Tue, 18 Oct 2016, Kieran Bingham wrote:
> Hi Pete,
>
> On 18/10/16 16:07, Peter Griffin wrote:
> > proc.py:22:1: E302 expected 2 blank lines, found 1
> > proc.py:200:1: E302 expected 2 blank lines, found 1
> >
> > Signed-off-by: Peter Griffin <[email protected]>
> > ---
> > scripts/gdb/linux/proc.py | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/scripts/gdb/linux/proc.py b/scripts/gdb/linux/proc.py
> > index f20fcfa..2d6f74e 100644
> > --- a/scripts/gdb/linux/proc.py
> > +++ b/scripts/gdb/linux/proc.py
> > @@ -18,6 +18,7 @@ from linux import tasks
> > from linux import lists
> > from struct import *
> >
> > +
>
> This was added by patch 1, and can be squashed there.
Doh, I had deliberately done it as a separate commit, as I thought it was
a pre-existing pep8 error.
Will squash in v2.
regards,
Peter.
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 <[email protected]>
> > ---
> > 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.
regards,
Peter
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 <[email protected]>
>>> ---
>>> 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
--
Siemens AG, Corporate Technology, CT RDA ITP SES-DE
Corporate Competence Center Embedded Linux
Hi Jan,
On Tue, 18 Oct 2016, Jan Kiszka wrote:
> 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 <[email protected]>
> >>> ---
> >>> 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
>
Thanks for the tip, that is very cool!
Will add gdb.COMPLETE_FILENAME in V2.
regads,
Peter.
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 <[email protected]>
> > ---
> > 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