On Wed, Jul 14, 2021 at 5:11 AM Tom Rini <tr...@konsulko.com> wrote: > > On Tue, Jul 13, 2021 at 10:35:03PM +0200, Marek Vasut wrote: > > On 7/13/21 8:11 PM, Tom Rini wrote: > > > On Tue, Jul 13, 2021 at 07:50:49PM +0200, Marek Vasut wrote: > > > > On 7/13/21 6:47 PM, Simon Glass wrote: > > > > > Hi Marek, > > > > > > > > > > On Tue, 13 Jul 2021 at 08:53, Marek Vasut <ma...@denx.de> wrote: > > > > > > > > > > > > On 7/13/21 4:41 PM, Tom Rini wrote: > > > > > > > On Tue, Jul 13, 2021 at 04:35:38PM +0200, Marek Vasut wrote: > > > > > > > > On 7/13/21 3:47 PM, Tom Rini wrote: > > > > > > > > > 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? > > > > > > > > > > > > > > > > Remember, there is also falcon boot. And we definitely have to > > > > > > > > be able to > > > > > > > > have old u-boot (SPL) boot new fitImage and vice versa. > > > > > > > > > > > > > > I don't follow you, sorry. But since you seem to have the best > > > > > > > understanding of where all of the cases something could go wrong > > > > > > > here, > > > > > > > can you perhaps post an RFC patch? That is likely to be clearer > > > > > > > than > > > > > > > another long thread here. > > > > > > > > > > > > I don't follow you, sorry. I believe the revert did the right thing > > > > > > and > > > > > > new systems should use mkimage -E when generating fitImages, to > > > > > > avoid > > > > > > the string alignment problem. That is all. > > > > > > > > > > Using -E should be optional and things really should work without it. > > > > > > > > See the DTSpec, I don't think that is possible unless you relocate > > > > fitImage > > > > components, and if you want fast boot time esp. in SPL, that is not > > > > good. > > > > > > This is why I've asked you to make up some patch to perhaps highlight > > > the problem. Ensuring that the device tree, which is small, is also > > > 8-byte aligned, shouldn't be a big problem nor performance hit. I'm not > > > sure where the problem case is that isn't "user put things they control > > > in a bad spot, fail and tell them why" but I could just be missing a > > > case. > > > > The fail case is this: > > - you update SPL with this 8 byte alignment change > > - you have older kernel fitImage with embedded DT for falcon mode > > - system no longer boots because there is off-by-4 error in the DT > > address passed to the kernel > > OK. Then I think the answer is what I said recently in another part of > this thread, we need to split "find the fdt" from "align the fdt". The > fdt can come to us with any alignment it happens to have, but we can't > use that fdt in-place unless it's correctly aligned. In the case of > falcon mode, it needs to end up at CONFIG_SYS_SPL_ARGS_ADDR. The case > of passing it on to U-Boot proper is where we have at best a hack right > now (as noted by fdt_hack in common/spl/spl.c). That would be a place > to, as has been also suggested in this thread, pass along more correctly > where the device tree in memory is.
Where are we on this issue? Regards, Bin
