On Mon, Jul 12, 2021 at 05:38:33PM +0200, Marek Vasut wrote: > On 7/12/21 5:15 PM, Tom Rini wrote: > > On Mon, Jul 12, 2021 at 01:36:14PM +0800, Bin Meng wrote: > > > On Mon, Jul 12, 2021 at 1:21 PM Reuben Dowle <reuben.do...@4rf.com> wrote: > > > > > > > > I submitted an almost identical patch. See > > > > https://github.com/u-boot/u-boot/commit/eb39d8ba5f0d1468b01b89a2a464d18612d3ea76 > > > > > > > > This patch eventually had to be reverted > > > > (https://github.com/u-boot/u-boot/commit/5675ed7cb645f5ec13958726992daeeed16fd114), > > > > because it was causing issues on some platforms that had FIT on 32 bit > > > > boundary. However I continue to use it in production code, as without > > > > it the boot on my platform aborts. > > > > > > > > I don't have time to investigate why this was happening, but you need > > > > to check this code won't just cause exactly the same faults. > > > > > > Thanks for your information. > > > > > > +Marek who did the revert > > > > > > The revert commit message says: > > > > > > "The commit breaks booting of fitImage by SPL, the system simply > > > hangs. This is because on arm32, the fitImage and all of its content > > > can be aligned to 4 bytes and U-Boot expects just that." > > > > > > I don't understand this. If an address is aligned to 8, it is already > > > aligned to 4, so how did this commit make the system hang on arm32? > > > > I think this had something to do with embedding contents somewhere in > > the image? There is a thread on the ML from then but I don't know how > > informative it will end up being. > > If I recall this correctly, DT node alignment is 4 byte and that is what DTC > emits. If you have fitImage with embedded data, you basically end up with > > / { > prop1 = "string1"; > prop2 = "string2"; > }; > > where the "string2" is aligned to 4 bytes. And that is what U-Boot expects > when it tries to access those data in-place in SPL. > > The problem with the reverted patch was that it made U-Boot assume the > alignment is 8 bytes, and that actually works only if you use fitImage with > external data (mkimage -E), but with embedded data (mkimage default) not so > much. That caused off-by-4 error in some cases and that made the SPL hang. > > > > Note, as I indicated in this patch, now with libfdt 1.6.1, the > > > alignment to 8 byte is a must-have. So we have to do such alignment > > > anyway. > > > > > > @Tom may fill in why libfdt commit commit 5e735860c478 ("libfdt: Check > > > for 8-byte address alignment in fdt_ro_probe_()") was made to have the > > > 8-byte alignment requirement. > > > > Note that it's not so much since libfdt 1.6.1 but that since always the > > device tree has required 8 byte alignment. > > DT alignment was always 4 byte , no ?
I'm pretty sure, no, 8 byte base alignment is a pretty much always thing. I don't have a reference handy but I also know I couldn't have convinced dgibson to add the check otherwise. -- Tom
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