On Sat, Mar 6, 2021 at 1:45 AM Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx> wrote: > > On Wed, Mar 03, 2021 at 02:37:55PM -0600, Rob Herring wrote: > > On Wed, Mar 3, 2021 at 1:33 PM Paul Cercueil <paul@xxxxxxxxxxxxxxx> wrote: > > > > > > Since 5.12-rc1, the Device Tree blob must now be properly aligned. > > > > I had checked the other built-in cases as microblaze broke too, but > > missed some of the many ways MIPS can have a dtb. Appended and > > built-in DTBs were supposed to be temporary. :( > > and a fdt can also be provided by firmware. And according to spec > there is no aligmnet requirement. So this whole change will break > then. What was the reason for the whole churn ? There was a long discussion on devicetree-compiler list a few months ago. In summary, a while back libfdt switched to accessors from raw pointer accesses to avoid any possible unaligned accesses (is MIPS always okay with unaligned accesses?). This was determined to be a performance regression and an overkill as the DT structure itself should always be naturally aligned if the dtb is 64-bit aligned. I think 32-bit aligned has some possible misaligned accesses. As part of this, a dtb alignment check was added. So worst case, we could disable that if need be. Rob
