Hi Simon,
On 5/4/26 2:49 PM, Simon Glass wrote:
Hi Quentin,
On Mon, 27 Apr 2026 at 03:14, Quentin Schulz <[email protected]> wrote:
Hi Simon, Marek,
On 4/22/26 4:31 AM, Simon Glass wrote:
When producing a DTB from fdtgrep, there is no way to reserve extra
space so that more nodes/properties can be added at runtime without
growing totalsize first.
Ok but why is that an issue? What is the actual usecase? What I'm afraid
of is that you pad enough and you hit random bugs because you forget
that adding enough properties can now hit the size limit and you forgot
to add the logic to resize/grow the fdt when it's too small to fit new
properties.
I'm going to leave this question to Marek :-)
Add a -B/--pad option that appends a caller-specified number of free
bytes after the strings section and grows totalsize accordingly. The
padding is applied after fdt_pack(), so it is not reclaimed when -r is
used.
Suggested-by: Marek Vasut <[email protected]>
Signed-off-by: Simon Glass <[email protected]>
---
tools/binman/btool/fdtgrep.py | 3 ++-
tools/fdtgrep.c | 31 ++++++++++++++++++++++++++++++-
2 files changed, 32 insertions(+), 2 deletions(-)
diff --git a/tools/binman/btool/fdtgrep.py b/tools/binman/btool/fdtgrep.py
index 446b2f4144b..7b393241878 100644
--- a/tools/binman/btool/fdtgrep.py
+++ b/tools/binman/btool/fdtgrep.py
@@ -16,9 +16,10 @@ Output formats are:
dtb - device tree blob (sets -Hmt automatically)
bin - device tree fragment (may not be a valid .dtb)
-Options: -[haAc:b:C:defg:G:HIlLmn:N:o:O:p:P:rRsStTvhV]
+Options: -[haAB:c:b:C:defg:G:HIlLmn:N:o:O:p:P:rRsStTvhV]
-a, --show-address Display address
-A, --colour Show all nodes/tags, colour those that
match
+ -B, --pad <arg> Append free space to the output FDT, for
later growth
-b, --include-node-with-prop <arg> Include contains containing property
-c, --include-compat <arg> Compatible nodes to include in grep
-C, --exclude-compat <arg> Compatible nodes to exclude in grep
I'm tempted to remove this and just tell people to look at the
documentation in tools/fdtgrep.c. Especially since we don't actually
allow the user to pass any of those parameters themselves via the
bintool, so it isn't actually useful.
I would like fdtgrep to give useful help, though. It is a tool which
can stand alone.
Yes, but this here is docstring for the fdtgrep *Bintool* module which
actually doesn't support most of the arguments specified here. So I
would say it's more confusing to have it there than not have anything.
For sure we want to keep documentation of fdtgrep, the tool as in
tools/fdtgrep.c, complete and up-to-date!
Cheers,
Quentin
