Hi Chen-Yu, On Wed, 5 Jun 2024 at 03:48, Chen-Yu Tsai <wenst@xxxxxxxxxxxx> wrote: > > The kernel tree builds some "composite" DTBs, where the final DTB is the > result of applying one or more DTB overlays on top of a base DTB with > fdtoverlay. > > The FIT image specification already supports configurations having one > base DTB and overlays applied on top. It is then up to the bootloader to > apply said overlays and either use or pass on the final result. This > allows the FIT image builder to reuse the same FDT images for multiple > configurations, if such cases exist. > > The decomposition function depends on the kernel build system, reading > back the .cmd files for the to-be-packaged DTB files to check for the > fdtoverlay command being called. This will not work outside the kernel > tree. The function is off by default to keep compatibility with possible > existing users. > > To facilitate the decomposition and keep the code clean, the model and > compatitble string extraction have been moved out of the output_dtb > function. The FDT image description is replaced with the base file name > of the included image. > > Signed-off-by: Chen-Yu Tsai <wenst@xxxxxxxxxxxx> > --- > This is a feature I alluded to in my replies to Simon's original > submission of the make_fit.py script [1]. > > This is again made a runtime argument as not all firmware out there > that boot FIT images support applying overlays. Like my previous > submission for disabling compression for included FDT images, the > bootloader found in RK3399 and MT8173 Chromebooks do not support > applying overlays. Another case of this is U-boot shipped by development > board vendors in binary form (without upstream) in an image or in > SPI flash on the board that were built with OF_LIBFDT_OVERLAY=n. > These would fail to boot FIT images with DT overlays. One such > example is my Hummingboard Pulse. In these cases the firmware is > either not upgradable or very hard to upgrade. > > I believe there is value in supporting these cases. A common script > shipped with the kernel source that can be shared by distros means > the distro people don't have to reimplement this in their downstream > repos or meta-packages. For ChromeOS this means reducing the amount > of package code we have in shell script. > > [1] https://lore.kernel.org/linux-kbuild/20231207142723.GA3187877@xxxxxxxxxx/ > [2] > > scripts/Makefile.lib | 1 + > scripts/make_fit.py | 70 ++++++++++++++++++++++++++++++-------------- > 2 files changed, 49 insertions(+), 22 deletions(-) Reviewed-by: Simon Glass <sjg@xxxxxxxxxxxx> Some possible nits / changes below > > diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib > index 9f06f6aaf7fc..d78b5d38beaa 100644 > --- a/scripts/Makefile.lib > +++ b/scripts/Makefile.lib > @@ -522,6 +522,7 @@ quiet_cmd_fit = FIT $@ > cmd_fit = $(MAKE_FIT) -o $@ --arch $(UIMAGE_ARCH) --os linux \ > --name '$(UIMAGE_NAME)' \ > $(if $(findstring 1,$(KBUILD_VERBOSE)),-v) \ > + $(if $(FIT_DECOMPOSE_DTBS),--decompose-dtbs) \ > --compress $(FIT_COMPRESSION) -k $< @$(word 2,$^) > > # XZ > diff --git a/scripts/make_fit.py b/scripts/make_fit.py > index 263147df80a4..120f13e1323c 100755 > --- a/scripts/make_fit.py > +++ b/scripts/make_fit.py > @@ -22,6 +22,11 @@ the entire FIT. > Use -c to compress the data, using bzip2, gzip, lz4, lzma, lzo and > zstd algorithms. > > +Use -d to decompose "composite" DTBs into their base components and > +deduplicate the resulting base DTBs and DTB overlays. This requires the > +DTBs to be sourced from the kernel build directory, as the implementation > +looks at the .cmd files produced by the kernel build. > + > The resulting FIT can be booted by bootloaders which support FIT, such > as U-Boot, Linuxboot, Tianocore, etc. > > @@ -64,6 +69,8 @@ def parse_args(): > help='Specifies the architecture') > parser.add_argument('-c', '--compress', type=str, default='none', > help='Specifies the compression') > + parser.add_argument('-d', '--decompose-dtbs', action='store_true', > + help='Decompose composite DTBs into base DTB and overlays') I wonder if we should reserve -d for --debug? I don't have a strong opinion though. > parser.add_argument('-E', '--external', action='store_true', > help='Convert the FIT to use external data') > parser.add_argument('-n', '--name', type=str, required=True, > @@ -140,12 +147,12 @@ def finish_fit(fsw, entries): > fsw.end_node() > seq = 0 > with fsw.add_node('configurations'): > - for model, compat in entries: > + for model, compat, files in entries: > seq += 1 > with fsw.add_node(f'conf-{seq}'): > fsw.property('compatible', bytes(compat)) > fsw.property_string('description', model) > - fsw.property_string('fdt', f'fdt-{seq}') > + fsw.property('fdt', b''.join([b'fdt-%d\x00' % x for x in files])) This looks right to me. It would be nice to use an f string but I don't know how to do that with bytes. But do you need the inner [] ? > fsw.property_string('kernel', 'kernel') > fsw.end_node() > > @@ -193,21 +200,9 @@ def output_dtb(fsw, seq, fname, arch, compress): > fname (str): Filename containing the DTB > arch: FIT architecture, e.g. 'arm64' > compress (str): Compressed algorithm, e.g. 'gzip' > - > - Returns: > - tuple: > - str: Model name > - bytes: Compatible stringlist > """ > with fsw.add_node(f'fdt-{seq}'): > - # Get the compatible / model information > - with open(fname, 'rb') as inf: > - data = inf.read() > - fdt = libfdt.FdtRo(data) > - model = fdt.getprop(0, 'model').as_str() > - compat = fdt.getprop(0, 'compatible') > - > - fsw.property_string('description', model) > + fsw.property_string('description', os.path.basename(fname)) > fsw.property_string('type', 'flat_dt') > fsw.property_string('arch', arch) > fsw.property_string('compression', compress) > @@ -215,7 +210,6 @@ def output_dtb(fsw, seq, fname, arch, compress): > with open(fname, 'rb') as inf: > compressed = compress_data(inf, compress) > fsw.property('data', compressed) > - return model, compat > > > def build_fit(args): > @@ -235,6 +229,7 @@ def build_fit(args): > fsw = libfdt.FdtSw() > setup_fit(fsw, args.name) > entries = [] > + fdts = collections.OrderedDict() > > # Handle the kernel > with open(args.kernel, 'rb') as inf: > @@ -243,12 +238,43 @@ def build_fit(args): > write_kernel(fsw, comp_data, args) > > for fname in args.dtbs: > - # Ignore overlay (.dtbo) files > - if os.path.splitext(fname)[1] == '.dtb': > - seq += 1 > - size += os.path.getsize(fname) > - model, compat = output_dtb(fsw, seq, fname, args.arch, args.compress) > - entries.append([model, compat]) > + # Ignore non-DTB (*.dtb) files > + if os.path.splitext(fname)[1] != '.dtb': > + continue > + > + # Get the compatible / model information > + with open(fname, 'rb') as inf: > + data = inf.read() > + fdt = libfdt.FdtRo(data) > + model = fdt.getprop(0, 'model').as_str() > + compat = fdt.getprop(0, 'compatible') > + > + if args.decompose_dtbs: > + # Check if the DTB needs to be decomposed > + path, basename = os.path.split(fname) > + cmd_fname = os.path.join(path, f'.{basename}.cmd') > + with open(cmd_fname, 'r', encoding='ascii') as inf: > + cmd = inf.read() > + > + if 'scripts/dtc/fdtoverlay' in cmd: > + # This depends on the structure of the composite DTB command > + files = cmd.split() > + files = files[files.index('-i')+1:] spaces around + > + else: > + files = [fname] > + else: > + files = [fname] I do wonder if the code from '# Get the compatible' to here would be better in a separate, documented function, to keep things easier to understand? > + > + for fn in files: > + if fn not in fdts: > + seq += 1 > + size += os.path.getsize(fn) > + output_dtb(fsw, seq, fn, args.arch, args.compress) > + fdts[fn] = seq > + > + files_seq = [fdts[fn] for fn in files] > + > + entries.append([model, compat, files_seq]) > > finish_fit(fsw, entries) > > -- > 2.45.1.288.g0e0cd299f1-goog > Regards, Simon
