https://sourceware.org/bugzilla/show_bug.cgi?id=29861
Bug ID: 29861
Summary: ld: Output Section Type can't be Overwritten /
Documentation Unclear
Product: binutils
Version: 2.39
Status: UNCONFIRMED
Severity: minor
Priority: P2
Component: ld
Assignee: unassigned at sourceware dot org
Reporter: phip1611 at gmail dot com
Target Milestone: ---
Since GNU binutils 2.39, specifically commit c212f39d (2022-02-16), the linker
script language allows setting a dedicated type for an output section
(https://sourceware.org/binutils/docs/ld/Output-Section-Type.html). This works
with sections that are only defined by content provided in the linker script,
as the following example shows:
SECTIONS {
foobar (TYPE = SHT_PROGBITS) : { BYTE(1) }
}
readelf shows exactly the expected type for the foobar section.
However, GNU ld ignores this type when an output section contains input
sections that already have a certain section type. The following is not
possible:
.bss . (TYPE = SHT_PROGBITS) :
{
*(COMMON)
*(.bss)
}
The type is always SHT_NOBITS, no matter what the linker script specifies. This
is not only the case for special pre-defined sections, such as .bss. It also
applies to custom sections. For example, take a look at the following GAS
example:
.section .foobar, "ax", @nobits
zeroed_buffer:
.fill 1024, 1, 0
The section will always be of type SHT_NOBITS, even if the linker script
specifies
.foobar . (TYPE=SHT_PROGBITS) :
{
*(.foobar)
}
So I wonder, is this a bug or intended? If it is intended, the documentation
should describe more precisely what this feature is capable of and what the
limits are.
PS: I work in a project where we need to ensure that memsize==filesize for each
section. One solution is to link *(COMMON) and *(.bss) into .data which is of
type SHT_PROGBITS. However, I thought the new approach might be more obvious
when someone looks at the linker script. However, it doesn't work as I expect.
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