Should I submit a new patch with the alignment set to 8 bytes? I would think a hard coded 8 bytes would not be the best solution, since not all architectures will need that much alignment. I suspect some would work with any alignment, and most 32-bit archs would be fine with 4-byte alignment.
Our released software is actually using a patch to align to 4096 bytes, but I knew that was unnecessarily large. I was not really sure what would be an appropriate value here, and took a guess at ARCH_DMA_MINALIGN when I cleaned it up for submitting upstream. Is there a better define to use? I am also interested to know where the 8 byte alignment requirement is documented. Reuben > -----Original Message----- > From: Tom Rini <tr...@konsulko.com> > Sent: Tuesday, 25 August 2020 2:27 am > To: Reuben Dowle <reuben.do...@4rf.com> > Cc: u-boot@lists.denx.de > Subject: Re: [PATCH] Fix data abort caused by mis-aligning fit data in > > On Fri, Jul 24, 2020 at 05:19:39AM +0000, Reuben Dowle wrote: > > > Attempting to place device tree immediately after an image in memory > > can lead to mis-aligned data accesses if that image size is not > > divisible by the alignment requirements of the architecture. > > > > Data aborts caused by this were observed on a custom Marvel A388 based > > system, where the image was a uboot FIT file. The total size varies > > depending on the uboot device tree size, which does not always lead to > correct alignment. > > > > Signed-off-by: Reuben Dowle <reuben.do...@4rf.com> > > --- > > common/spl/spl_fit.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/common/spl/spl_fit.c b/common/spl/spl_fit.c index > > 365104f..d221075 100644 > > --- a/common/spl/spl_fit.c > > +++ b/common/spl/spl_fit.c > > @@ -349,9 +349,9 @@ static int spl_fit_append_fdt(struct > > spl_image_info *spl_image, > > > > /* > > * Use the address following the image as target address for the > > - * device tree. > > + * device tree. Ensure that address is appropriately aligned. > > */ > > - image_info.load_addr = spl_image->load_addr + spl_image->size; > > + image_info.load_addr = ALIGN(spl_image->load_addr + spl_image- > >size, > > +ARCH_DMA_MINALIGN); > > > > /* Figure out which device tree the board wants to use */ > > node = spl_fit_get_image_node(fit, images, FIT_FDT_PROP, > index++); > > Sorry for the late reply here. While we do need to ensure that the device > tree is aligned, the documented alignment requirement for all platforms is 8 > byte, so we should document and use that here in case future platforms > require a higher alignment. Thanks! > > -- > Tom
