Hi Tom, On Sat, Aug 8, 2026 at 10:11 PM Tom Rini <[email protected]> wrote: > > On Sat, Aug 08, 2026 at 01:02:02PM +0400, Alexey Charkov wrote: > > Hi Simon, > > > > On Wed, Aug 5, 2026 at 11:34 PM Simon Glass <[email protected]> wrote: > > > > > > Hi Alexey, > > > > > > On 2026-08-05T14:47:38, Alexey Charkov <[email protected]> wrote: > > > > pylibfdt: Grow the FdtSw buffer geometrically > > > > > > > > Every expansion copies the whole tree into a freshly allocated buffer, > > > > so > > > > growing by a fixed amount makes building a tree cost time quadratic in > > > > its size. This is especially painful when assembling larger FIT images > > > > with > > > > binman, as it assembles the image with the data inline. > > > > > > > > Grow by at least as much as the tree already holds, which is what > > > > variable > > > > sized arrays usually do specifically to avoid such excessive copying. > > > > > > > > With this change, building a Rockchip TF-A+Falcon image whose FIT > > > > carries > > > > a 31 MiB kernel takes 33.1 s rather than 44.4 s, with binman itself down > > > > from 25.3 s to 14.0 s, as 7139 reallocations become 187. The images > > > > produced are byte-identical and the binman and dtoc test results are > > > > unaffected. > > > > > > > > Signed-off-by: Alexey Charkov <[email protected]> > > > > > > > > scripts/dtc/pylibfdt/libfdt.i_shipped | 8 ++++++-- > > > > 1 file changed, 6 insertions(+), 2 deletions(-) > > > > > > This is a _shipped file from upstream dtc, so any change here will be > > > reverted on the next resync. Please can you send this to the dtc > > > project first (see https://github.com/dgibson/dtc) and reference the > > > upstream commit / PR in the U-Boot commit message, similar to how > > > a63456b9191 links to dgibson/dtc PR 154. Otherwise the improvement > > > will be lost. > > > > > > > @@ -808,7 +812,7 @@ class FdtSw(FdtRo): > > > > if check_err(val, QUIET_NOSPACE) < 0: > > > > - self.resize(len(self._fdt) + self.INC_SIZE) > > > > + self.resize(len(self._fdt) + max(len(self._fdt), > > > > self.INC_SIZE)) > > > > > > Logic looks correct - doubling gives amortised O(n) total copying, and > > > the INC_SIZE floor keeps small trees from taking many tiny growths. > > > Nice measurement in the commit message too. > > > > Merged upstream: https://github.com/dgibson/dtc/pull/189 > > > > Shall I spin a new version of this one to mention the upstream commit? > > Yes please, and are there other changes we need to merge in from > upstream as well, in the pylibfdt portion?
I've also added public accessors for address-cells, size-cells along with add/delete methods for memory reservations, which David merged earlier today [1]. It would be great to pull those in, too, while we are at it. They are useful for the Falcon mode via TF-A series I'm working on [2] but haven't yet posted the new version due to breakage in am335x_evm which I am yet to fix. I could send them together with this change here as a separate mini-series if that works (i.e. ahead of the Falcon changes which rely on them). [1] https://github.com/dgibson/dtc/pull/190 [2] https://git.u-boot-project.org/u-boot/contributors/alchark/u-boot/-/tree/b4/atf-falcon?ref_type=heads Best regards, Alexey
