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https://issues.apache.org/jira/browse/MYNEWT-509?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15893080#comment-15893080
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Christopher Collins commented on MYNEWT-509:
--------------------------------------------
Unfortunately, I wasn't able to accomplish this with linker script
modifications. For completeness, here is what I tried:
h4. Reduce size of FLASH region by (tlvs-size + boot-trailer-size)
{noformat}
MEMORY
{
FLASH (rx) : ORIGIN = 0x00008000, LENGTH = 0x3a000 - _imgtlvs_size -
_boot_trailer_size
RAM (rwx) : ORIGIN = 0x20000000, LENGTH = 0x10000
}
{noformat}
Where _imgtlvs_size and _boot_trailer_size are linker script variables. This
elicits the following ld error:
{quote}
Error: /Users/ccollins/repos/mynewt/core/hw/bsp/nrf52dk/nrf52xxaa.ld:41:
nonconstant expression for length
{quote}
_boot_trailer_size needs to be a variable because its value depends on the
MCU's minimum flash write size.
h4. Create NOLOAD sections corresponding to the TLVs and boot trailer.
{noformat}
.imgtlvs (NOLOAD):
{
. = . + _imgtlvs_size;
} > FLASH
.boottrailer (NOLOAD):
{
. = . + _boot_trailer_size;
} > FLASH
{noformat}
This is what we do to reserve 32 bytes for the image header. Sadly, this
doesn't work in this case. Since these sections don't come at the start of the
image (they are at the end), they are zero-filled in the generated binary.
This is obviously not what we want. We need these sections to be unwritten.
h4. Adjust the location counter by hand
{noformat}
__exidx_end = .;
. += _imgtlvs_size;
. += _boot_trailer_size;
__etext = .;
{noformat}
This works in that __etext gets the correct value. Unfortunately, ld does not
report an error when these adjustments push the location counter beyond the end
of flash. The linker only seems to report an error if it tries to place a
section outside the bounds of the region.
> Linker script should limit image size to allow for trailer
> ----------------------------------------------------------
>
> Key: MYNEWT-509
> URL: https://issues.apache.org/jira/browse/MYNEWT-509
> Project: Mynewt
> Issue Type: Bug
> Reporter: Christopher Collins
> Assignee: Christopher Collins
> Fix For: v1_0_0_rel
>
>
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