On Mon, Jul 12, 2021 at 11:01:24AM -0500, Alex G. wrote: > On 7/12/21 10:15 AM, 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. > > It's true that the flat devicetree spec requires an 8-byte alignment, even > on 32-bit. The issues here are specific to u-boot. > > SPL and u-boot have to agree where u-boot's FDT is located. We'll look at > two cases: > 1) u-boot as a FIT (binary and FDT separately loaded) > 2) u-boot with embedded FDT > > In case (1) SPL must place the FDT at a location where u-boot will find it. > The current logic is > SPL: fdt = ALIGN_4(u_boot + u_boot_size) > u-boot: fdt = ALIGN_4(u_boot + u_boot_size) > > In case (2), SPL's view of the FDT is not relevant, but instead the build > system must place the FDT correctly: > build: fdt >> u-boot.bin > u-boot: fdt = ALIGN_4(u_boot + u_boot_size) > > We have 3 places that must agree. A correct and complete patch could change > all three, but one has to consider compatibility issues when crossing u-boot > and SPL versions. > > I had proposed in the revert discussion that SPL use r2 or similar mechanism > to pass the location of the FDT to u-boot.
I'm not sure that we need to worry too much about mix-and-match SPL/U-Boot, but documenting what to go change if you must do it somewhere under doc/ would be good. I think we can just switch to ALIGN(8) not ALIGN(4) and be done with it? -- Tom
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