Re: [PATCH V2 2/2] scripts: dtc: Build fdtoverlay and fdtdump tools

Frank Rowand
2021-01-19T18:27:54Z

On 1/6/21 11:15 PM, Viresh Kumar wrote:
> We will start building overlays for platforms soon in the kernel and
> would need these tools going forward. Lets start building them.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
> scripts/dtc/Makefile | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/scripts/dtc/Makefile b/scripts/dtc/Makefile
> index 4852bf44e913..c607980a5c17 100644
> --- a/scripts/dtc/Makefile
> +++ b/scripts/dtc/Makefile
> @@ -1,12 +1,18 @@
> # SPDX-License-Identifier: GPL-2.0
> # scripts/dtc makefile
>
> -hostprogs-always-$(CONFIG_DTC) += dtc
> +hostprogs-always-$(CONFIG_DTC) += dtc fdtdump fdtoverlay
> hostprogs-always-$(CHECK_DT_BINDING) += dtc
>
> dtc-objs := dtc.o flattree.o fstree.o data.o livetree.o treesource.o \
> srcpos.o checks.o util.o
> dtc-objs += dtc-lexer.lex.o dtc-parser.tab.o
> +fdtdump-objs := fdtdump.o util.o
> +

# The upstream project builds libfdt as a separate library. We are choosing to
# instead directly link the libfdt object files into fdtoverly

> +libfdt_dir = libfdt
> +libfdt-objs := fdt.o fdt_ro.o fdt_wip.o fdt_sw.o fdt_rw.o fdt_strerror.o fdt_empty_tree.o fdt_addresses.o fdt_overlay.o
> +libfdt = $(addprefix $(libfdt_dir)/,$(libfdt-objs))
> +fdtoverlay-objs := $(libfdt) fdtoverlay.o util.o
>
> # Source files need to get at the userspace version of libfdt_env.h to compile
> HOST_EXTRACFLAGS += -I $(srctree)/$(src)/libfdt
>

In general, I am a proponent of using shared libraries (which the upstream project
builds by default) because if a security bug in the library is fixed, it is fixed
for all users of the library.

In this specific case, I actually prefer the implementation that the patch provides
(directly linking the library object files into fdtoverlay, which uses the library)
because it is the only user of the library _and_ fdtoverlay will not inadvertently
use the system wide libfdt if it happens to be installed (as it is on my system).

Any thoughts on this Rob?

-Frank