Re: [PATCH] lds: align u-boot-nodtb with 8 bytes boundary

[Tom Rini <trini@konsulko.com>]

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On Sat, Dec 17, 2022 at 11:14:41PM +0100, Mark Kettenis wrote:
> > From: Eugen Hristev <eugen.hristev@microchip.com>
> > Date: Thu, 15 Dec 2022 13:58:25 +0200
> > 
> > Newer DTC require that the DTB start address is aligned at 8 bytes.
> > In the u-boot.bin case, the u-boot-nodtb.bin is concatenated with the
> > DTB, but there is no alignment/padding to the next 8byte aligned address.
> > This causes the board to fail booting, because the FDT will claim
> > that the DTB inside u-boot.bin is not a valid DTB, it will fail with
> > -FDT_ERR_ALIGNMENT.
> > To solve this, have the u-boot binary `_end` aligned with 8 bytes.
> > The objcopy in the Makefile will create the u-boot-nodtb.bin and it has to
> > be truncated to 8 bytes to correspond to the u-boot.map file which will
> > have the `_end` aligned to 8 bytes.
> > The lds files which use devicetrees have been changed to align the `_end`
> > tag with 8 bytes.
> > 
> > This patch is also a prerequisite to have the possibility to update the
> > dtc inside u-boot to newer versions (1.6.1+)
> > 
> > Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
> > ---
> > Hi,
> > 
> > I could not test all affected boards, it's an impossible task.
> > I tried this on at91 boards which I have, and ran the CI on denx.
> > I cannot guarantee that no other boards are affected, so this patch is a bit
> > of an RFC.
> > If the u-boot-nodtb.bin does not have the size equal with the corresponding
> > one in u-boot.map, the binary_size_check will fail at build time with
> > something like this:
> > 
> > u-boot.map shows a binary size of 502684
> > but u-boot-nodtb.bin shows 502688
> > 
> > Thanks,
> > Eugen
> > 
> >  Makefile                                    | 2 ++
> >  arch/arm/cpu/armv8/u-boot.lds               | 4 ++--
> >  arch/arm/cpu/u-boot-spl.lds                 | 1 +
> >  arch/arm/cpu/u-boot.lds                     | 1 +
> >  arch/arm/lib/elf_arm_efi.lds                | 5 +++++
> >  arch/arm/mach-at91/arm926ejs/u-boot-spl.lds | 2 +-
> >  arch/arm/mach-at91/armv7/u-boot-spl.lds     | 2 +-
> >  arch/arm/mach-zynq/u-boot-spl.lds           | 2 +-
> >  arch/mips/cpu/u-boot.lds                    | 2 +-
> >  arch/sandbox/cpu/u-boot.lds                 | 6 ++++++
> >  arch/sh/cpu/u-boot.lds                      | 2 ++
> >  board/ti/am335x/u-boot.lds                  | 1 +
> >  tools/binman/test/u_boot_binman_embed.lds   | 2 +-
> >  13 files changed, 25 insertions(+), 7 deletions(-)
> > 
> > diff --git a/Makefile b/Makefile
> > index 9d84f96481..b4d387bcce 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -1317,6 +1317,8 @@ endif
> >  
> >  u-boot-nodtb.bin: u-boot FORCE
> >  	$(call if_changed,objcopy_uboot)
> > +# Make sure the size is 8 byte-aligned.
> > +	@truncate -s %8 $@
> 
> $ truncate
> ksh: truncate: not found
> 
> In other words: truncate(1) isn't a standard UNIX utility and not
> present on OpenBSD for example.  It isn't part of POSIX and therefore
> its usage is unportable.
> 
> Please find a different solution.

Ah yes. Can this perhaps be done with dd? A bit of looking around
suggests that this might be a portable way to truncate a file to say 512
bytes:
dd if=/dev/urandom of=testfile bs=1 count=500
dd if=/dev/null of=testfile bs=1 count=512

And then hexdump or whatever to see that the last 12 bytes are zero. Can
you please test this on OpenBSD?  We'll need some shell work to get
current byte size and make it 8-byte aligned, but that should be
portable at least.  Thanks!

-- 
Tom

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