On 2/6/26 12:41 AM, Tom Rini wrote:
Historically, when we have an appended device tree and also our
resulting binary will contain the BSS section, we have ensured that
everything will be where it's expected to be by declaring that the BSS
is overlayed with a symbol matches the end of the port
part ?
of the ELF binary
that is objcopy'd to the binary we concatenate with. This in turn means
that the logic to generate a "pad" file, which is the size found in the
__bss_size symbol, will be correct and then we can concatenate the
device tree and it will begin at __bss_size at run time.
With commit 5ffc1dcc26d3 ("arm: Remove rel.dyn from SPL linker scripts")
we removed this overlay as part of trying to ensure that we met both the
requirements of the device tree to be 8 byte aligned as well as that our
logic to generate the -pad file would match what ended up in the
resulting binary. While it was correct to remove an unused section it
did not solve ultimately solve the problem for all cases.
solve ultimately solve ... one solve is enough
To really fix the problem, we need to do two things. First, our final
section prior to _image_binary_end must be 8 byte aligned (for the case
of having a separate BSS and so our appended DTB exists at this
location). This cannot be '.binman_sym_table' as it may be empty, and in
turn the ELF type would be NOBITS and so not copied with objcopy. The
__u_boot_list section will never be empty
How can we be sure of that ?
, so it is our final section,
and ends with a '. = ALIGN(8)' statement. Second, as this is the end of
our copied data it is safe to declare that the BSS starts here, so use
the OVERLAY keyword to place the BSS here.
[...]
@@ -99,5 +99,6 @@ SECTIONS
ASSERT(_image_binary_end % 8 == 0, \
"_image_binary_end must be 8-byte aligned for device tree");
+
ASSERT(ADDR(.bss) % 8 == 0, \
".bss must be 8-byte aligned");
Please drop this extra newline ^ .
