+David. On 19-01-21, 11:12, Frank Rowand wrote: > On 1/12/21 2:28 AM, Viresh Kumar wrote: > > We will start building overlays for platforms soon in the kernel and > > would need fdtoverlay tool going forward. Lets start fetching and > > building it. > > > > While at it, also remove fdtdump.c file, which isn't used by the kernel. > > > > V4: > > - Don't fetch and build fdtdump.c > > - Remove fdtdump.c > > > > Viresh Kumar (3): > > scripts: dtc: Add fdtoverlay.c to DTC_SOURCE > > scripts: dtc: Build fdtoverlay tool > > scripts: dtc: Remove the unused fdtdump.c file > > > > scripts/dtc/Makefile | 6 +- > > scripts/dtc/fdtdump.c | 163 ------------------------------- > > scripts/dtc/update-dtc-source.sh | 6 +- > > 3 files changed, 8 insertions(+), 167 deletions(-) > > delete mode 100644 scripts/dtc/fdtdump.c > > > > My first inclination was to accept fdtoverlay, as is, from the upstream > project. > > But my experiences debugging use of fdtoverlay against the existing > unittest overlay files has me very wary of accepting fdtoverlay in > it's current form. > > As an exmple, adding an overlay that fails to reply results in the > following build messages: > > linux--5.11-rc> make zImage > make[1]: Entering directory '/local/frowand_nobackup/src/git_linus/build/dragon_linus_5.11-rc' > GEN Makefile > CALL /local/frowand_nobackup/src/git_linus/linux--5.11-rc/scripts/checksyscalls.sh > CALL /local/frowand_nobackup/src/git_linus/linux--5.11-rc/scripts/atomic/check-atomics.sh > CHK include/generated/compile.h > FDTOVERLAY drivers/of/unittest-data/static_test.dtb > > Failed to apply 'drivers/of/unittest-data/overlay.dtb': FDT_ERR_NOTFOUND > make[4]: *** [/local/frowand_nobackup/src/git_linus/linux--5.11-rc/drivers/of/unittest-data/Makefile:96: drivers/of/unittest-data/static_test.dtb] Error 1 > make[3]: *** [/local/frowand_nobackup/src/git_linus/linux--5.11-rc/scripts/Makefile.build:496: drivers/of/unittest-data] Error 2 > make[2]: *** [/local/frowand_nobackup/src/git_linus/linux--5.11-rc/scripts/Makefile.build:496: drivers/of] Error 2 > make[1]: *** [/local/frowand_nobackup/src/git_linus/linux--5.11-rc/Makefile:1805: drivers] Error 2 > make[1]: Leaving directory '/local/frowand_nobackup/src/git_linus/build/dragon_linus_5.11-rc' > make: *** [Makefile:185: __sub-make] Error 2 > > > The specific error message (copied from above) is: > > Failed to apply 'drivers/of/unittest-data/overlay.dtb': FDT_ERR_NOTFOUND > > which is cryptic and does not even point to the location in the overlay that > is problematic. If you look at the source of fdtoverlay / libfdt, you will > find that FDT_ERR_NOTFOUND may be generated in one of many places. > > I do _not_ want to do a full review of fdtoverlay, but I think that it is > reasonable to request enhancing fdtoverlay in the parent project to generate > usable error messages before enabling fdtoverlay in the Linux kernel tree. > > fdtoverlay in it's current form adds a potential maintenance burden to me > (as the overlay maintainer). I now have the experience of how difficult it > was to debug the use of fdtoverlay in the context of the proposed patch to > use it with the devicetree unittest overlay .dtb files. > > -Frank -- viresh
