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Date: Mon, 4 Jan 2016 15:29:48 -0600
From: Rob Herring <robh+dt@...nel.org>
To: Frank Rowand <frowand.list@...il.com>
Cc: Grant Likely <grant.likely@...aro.org>,
David Gibson <david@...son.dropbear.id.au>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
Linux Kernel list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] dtc: create tool to diff device trees
On Thu, Dec 31, 2015 at 3:12 AM, Frank Rowand <frowand.list@...il.com> wrote:
> From: Frank Rowand <frank.rowand@...ymobile.com>
>
> Create script to diff device trees.
>
> The device tree can be in any of the forms recognized by the dtc compiler:
> - source
> - binary blob
> - file system tree (from /proc/devicetree)
>
> If the device tree is a source file, then it is pre-processed in the
> same way as it would be when built in the linux kernel source tree
> before diffing.
In general, I'd like to see some of this move to dtc and the kernel
dependencies minimized.
>
> Signed-off-by: Frank Rowand <frank.rowand@...ymobile.com>
> ---
>
> Tools to develop and debug device tree are somewhat inadequate. This is a
> small step in improving the situation.
>
> Rationale for and examples of using the script are provided in slides
> 1 - 78 of the elce 2015 presentation "Solving Device Tree Issues",
> which can be found at:
>
> http://elinux.org/images/0/04/Dt_debugging_elce_2015_151006_0421.pdf
>
> (The script was named dtdiff instead of dtx_diff in the presentation.)
>
>
> scripts/dtc/dtx_diff | 368 +++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 368 insertions(+)
>
> Index: b/scripts/dtc/dtx_diff
> ===================================================================
> --- /dev/null
> +++ b/scripts/dtc/dtx_diff
> @@ -0,0 +1,368 @@
> +#! /bin/bash
Add "-e" by default?
> +
> +# Copyright (C) 2015 Frank Rowand
> +#
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; version 2 of the License.
> +
> +
> +usage() {
> +
> + # use spaces instead of tabs in the usage message
> + cat >&2 <<eod
> +
> +Usage:
> +
> + `basename $0` DTx
> + decompile DTx
> +
> + `basename $0` DTx_1 DTx_2
> + diff DTx_1 and DTx_2
> +
> +
> + -f print full dts in diff (--unified=99999)
> + -h synonym for --help
> + -help synonym for --help
> + --help print this message and exit
> + -s SRCTREE linux kernel source tree is at path SRCTREE
> + (default is current directory)
> + -S linux kernel source tree is at root of current git repo
Can't this be detected? There are some cases of kernel trees which are
not in git.
> + -u unsorted, do not sort DTx
> +
> +
> +Each DTx is processed by the dtc compiler to produce a sorted dts source
> +file. If DTx is a dts source file then it is pre-processed in the same
> +manner as done for the compile of the dts source file in the Linux kernel
> +build system ('#include' and '/include/' directives are processed).
> +
> +If two DTx are provided, the resulting dts source files are diffed.
> +
> +If DTx is a directory, it is treated as a DT subtree, such as
> + /proc/device-tree.
> +
> +If DTx contains the binary blob magic value in the first four bytes,
> + it is treated as a binary blob (aka .dtb or FDT).
> +
> +Otherwise DTx is treated as a dts source file (aka .dts).
> +
> + If this script is not run from the root of the linux source tree,
> + and DTx utilizes '#include' or '/include/' then the path of the
> + linux source tree can be provided by '-s SRCTREE' or '-S' so that
> + include paths will be set properly.
> +
> + The shell variable \${ARCH} must provide the architecture containing
> + the dts source file for include paths to be set properly for '#include'
> + or '/include/' to be processed.
> +
> + If DTx_1 and DTx_2 are in different architectures, then this script
> + may not work since \${ARCH} is part of the include path. Two possible
> + workarounds:
> +
> + `basename $0` \\
> + <(ARCH=arch_of_dtx_1 `basename $0` DTx_1) \\
> + <(ARCH=arch_of_dtx_2 `basename $0` DTx_2)
> +
> + `basename $0` ARCH=arch_of_dtx_1 DTx_1 >tmp_dtx_1.dts
> + `basename $0` ARCH=arch_of_dtx_2 DTx_2 >tmp_dtx_2.dts
> + `basename $0` tmp_dtx_1.dts tmp_dtx_2.dts
> + rm tmp_dtx_1.dts tmp_dtx_2.dts
> +
> + If DTx_1 and DTx_2 are in different directories, then this script will
> + add the path of DTx_1 and DTx_2 to the include paths. If DTx_2 includes
> + a local file that exists in both the path of DTx_1 and DTx_2 then the
> + file in the path of DTx_1 will incorrectly be included. Possible
> + workaround:
> +
> + `basename $0` DTx_1 >tmp_dtx_1.dts
> + `basename $0` DTx_2 >tmp_dtx_2.dts
> + `basename $0` tmp_dtx_1.dts tmp_dtx_2.dts
> + rm tmp_dtx_1.dts tmp_dtx_2.dts
> +
> +eod
> +}
> +
> +
> +compile_to_dts() {
> +
> + dtx="$1"
> +
> + if [ -d "${dtx}" ] ; then
> +
> + # ----- input is file tree
> +
> + if ( ! ${DTC} -I fs ${dtx} ) ; then
> + exit 3
> + fi
> +
> + elif [ -f "${dtx}" ] && [ -r "${dtx}" ] ; then
> +
> + magic=`hexdump -n 4 -e '/1 "%02x"' ${dtx}`
> + if [ "${magic}" = "d00dfeed" ] ; then
Perhaps this auto-detection should be part of dtc?
> +
> + # ----- input is FDT (binary blob)
> +
> + if ( ! ${DTC} -I dtb ${dtx} ) ; then
> + exit 3
> + fi
> +
> + else
> +
> + # ----- input is DTS (source)
> +
> + if ( cpp ${cpp_flags} -x assembler-with-cpp ${dtx} | ${DTC} -I dts ) ; then
> + return
> + fi
> +
> + echo "" >&2
> + echo "Possible hints to resolve the above error:" >&2
> + echo " (hints might not fix the problem)" >&2
> +
> + hint_given=0
> +
> + if [ "${ARCH}" = "" ] ; then
> + hint_given=1
> + echo "" >&2
> + echo " shell variable \$ARCH not set" >&2
> + fi
> +
> + dtx_arch=`echo "/${dtx}" | sed -e 's|.*/arch/||' -e 's|/.*||'`
> +
> + if [ "${dtx_arch}" != "" -a "${dtx_arch}" != "${ARCH}" ] ; then
> + hint_given=1
> + echo "" >&2
> + echo " architecture ${dtx_arch} is in file path, but" >&2
> + echo " does not match shell variable \$ARCH (${ARCH})" >&2
> + fi
> +
> + if [ ! -d ${srctree}/arch/${ARCH} ] ; then
> + hint_given=1
> + echo "" >&2
> + echo " ${srctree}/arch/${ARCH}/ does not exist" >&2
> + echo " Is \$ARCH='${ARCH}' correct?" >&2
> + echo " Possible fix: use '-s' option" >&2
> +
> + git_root=`git rev-parse --show-toplevel 2>/dev/null`
> + if [ -d ${git_root}/arch/ ] ; then
> + echo " Possible fix: use '-S' option" >&2
> + fi
> + fi
> +
> + if [ $hint_given = 0 ] ; then
> + echo "" >&2
> + echo " No hints available." >&2
> + fi
> +
> + echo "" >&2
> +
> + exit 3
> +
> + fi
> + else
> + echo "" >&2
> + echo "ERROR: ${dtx} does not exist or is not readable" >&2
> + echo "" >&2
> + exit 2
> + fi
> +
> +}
> +
> +
> +# ----- start of script
> +
> +cmd_diff=0
> +diff_flags="-u"
> +dtx_file_1=""
> +dtx_file_2=""
> +dtc_sort="-s"
> +help=0
> +srctree=""
> +
> +
> +while [ $# -gt 0 ] ; do
> +
> + case $1 in
> +
> + -f )
> + diff_flags="--unified=999999"
> + shift
> + ;;
> +
> + -h | -help | --help )
> + help=1
> + shift
> + ;;
> +
> + -s )
> + srctree="$2"
> + shift 2
> + ;;
> +
> + -S )
> + git_root=`git rev-parse --show-toplevel 2>/dev/null`
> + srctree="${git_root}"
> + shift
> + ;;
> +
> + -u )
> + dtc_sort=""
> + shift
> + ;;
> +
> + *)
> + if [ "${dtx_file_1}" = "" ] ; then
> + dtx_file_1="$1"
> + elif [ "${dtx_file_2}" = "" ] ; then
> + dtx_file_2="$1"
> + else
> + echo "" >&2
> + echo "ERROR: Unexpected parameter: $1" >&2
> + echo "" >&2
> + exit 2
> + fi
> + shift
> + ;;
> +
> + esac
> +
> +done
> +
> +if [ "${srctree}" = "" ] ; then
> + srctree="."
> +fi
> +
> +if [ "${dtx_file_2}" != "" ]; then
> + cmd_diff=1
> +fi
> +
> +if (( ${help} )) ; then
> + usage
> + exit 1
> +fi
> +
> +# this must follow check for ${help}
> +if [ "${dtx_file_1}" = "" ]; then
> + echo "" >&2
> + echo "ERROR: parameter DTx required" >&2
> + echo "" >&2
> + exit 2
> +fi
> +
> +
> +# ----- prefer dtc from linux kernel, allow fallback to dtc in $PATH
> +
> +if [ "${KBUILD_OUTPUT:0:2}" = ".." ] ; then
> + __KBUILD_OUTPUT="${srctree}/${KBUILD_OUTPUT}"
> +elif [ "${KBUILD_OUTPUT}" = "" ] ; then
> + __KBUILD_OUTPUT="."
> +else
> + __KBUILD_OUTPUT="${KBUILD_OUTPUT}"
> +fi
> +
> +DTC="${__KBUILD_OUTPUT}/scripts/dtc/dtc"
> +
> +if [ ! -x ${DTC} ] ; then
> + __DTC="dtc"
> + if ( ! which ${__DTC} >/dev/null ) ; then
> +
> + # use spaces instead of tabs in the error message
> + cat >&2 <<eod
> +
> +ERROR: unable to find a 'dtc' program
> +
> + Preferred 'dtc' (built from Linux kernel source tree) was not found or
> + is not executable.
> +
> + 'dtc' is: ${DTC}
> +
> + If it does not exist, create it from the root of the Linux source tree:
> +
> + 'make scripts'.
> +
> + If not at the root of the Linux kernel source tree -s SRCTREE or -S
> + may need to be specified to find 'dtc'.
> +
> + If 'O=\${dir}' is specified in your Linux builds, this script requires
> + 'export KBUILD_OUTPUT=\${dir}' or add \${dir}/scripts/dtc to \$PATH
> + before running.
> +
> + If \${KBUILD_OUTPUT} is a relative path, then '-s SRCDIR', -S, or run
> + this script from the root of the Linux kernel source tree is required.
> +
> + Fallback '${__DTC}' was also not in \${PATH} or is not executable.
> +
> +eod
> + exit 2
> + fi
> + DTC=${__DTC}
> +fi
> +
> +
> +# ----- cpp and dtc flags same as for linux source tree build of .dtb files,
> +# plus directories of the dtx file(s)
> +
> +dtx_path_1_dtc_include="-i `dirname ${dtx_file_1}`"
> +
> +dtx_path_2_dtc_include=""
> +if (( ${cmd_diff} )) ; then
> + dtx_path_2_dtc_include="-i `dirname ${dtx_file_2}`"
> +fi
> +
> +cpp_flags="\
> + -nostdinc \
> + -I${srctree}/arch/${ARCH}/boot/dts \
> + -I${srctree}/arch/${ARCH}/boot/dts/include \
> + -I${srctree}/arch/${ARCH}/boot/dts/include/dt-bindings \
kernel doesn't use this path. The less dependency on ARCH, the better.
The dependency in the kernel is artificial.
> + -I${srctree}/drivers/of/testcase-data \
> + -undef -D__DTS__"
> +
> +_dts_makefile=""
> +
> +if [ -f ${srctree}/arch/${ARCH}/boot/dts/Makefile ] ; then
> + _dts_makefile="${srctree}/arch/${ARCH}/boot/dts/Makefile"
> +elif [ -f ${srctree}/arch/${ARCH}/boot/Makefile ] ; then
> + # arch/powerpc
> + _dts_makefile="${srctree}/arch/${ARCH}/boot/Makefile"
We need to move PPC to be in line with other arches rather than
working around it.
> +fi
> +
> +if [ "${_dts_makefile}" != "" ] ; then
> + arch_dtc_flags=`grep DTC_FLAGS ${_dts_makefile} \
We should just kill DTC_FLAGS being per arch. Plus it is only used for
padding, so it is irrelevant to this tool.
> + | grep -v "^#" \
> + | sed -e 's|.*=||' `
> +else
> + arch_dtc_flags=""
> +fi
> +
> +dtc_flags="\
> + -i ${srctree}/arch/${ARCH}/boot/dts/ \
> + -i ${srctree}/kernel/dts \
> + ${dtx_path_1_dtc_include} \
> + ${dtx_path_2_dtc_include} \
> + ${arch_dtc_flags}"
> +
> +DTC="${DTC} ${dtc_flags} -O dts -qq -f ${dtc_sort} -o -"
> +
> +
> +# ----- do the diff or decompile
> +
> +if (( ${cmd_diff} )) ; then
> +
> + diff ${diff_flags} \
> + <(compile_to_dts "${dtx_file_1}") \
> + <(compile_to_dts "${dtx_file_2}")
> +
> +else
> +
> + compile_to_dts "${dtx_file_1}"
> +
> +fi
> +
> +
> +# ==============================================================================
> +# ______________________________________________________________________________
> +# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
> +# ______________________________________________________________________________
> +# vi config follows:
> +#
> +# add "set modelines" to ~/.exrc or ~/.vimrc to set tabs automatically
> +# ex:set tabstop=4 shiftwidth=4 sts=4:
Kernel standard is 8 characters. I assume that applies to bash files too.
Rob
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