[memory-region] Error when section VMA does not fit in region by deepakshirkem · Pull Request #1102 · qualcomm/eld

deepakshirkem · 2026-04-25T12:46:13Z

Problem

Fixes #327

ELD was silently linking when a section's VMA was placedoutside its assigned memory region bounds:

MEMORY {
RAM : ORIGIN = 0x1000, LENGTH = 0x1000
}
SECTIONS {
.foo (0x2500) : { *(.text.foo) } >RAM  ← outside RAM!
}

Fix

Added check in postLayout() to verify each section's VMA fits within its assigned memory region bounds, matching LLD
behavior exactly:

Error: section '.foo' will not fit in region 'RAM':overflowed by 1288 bytes

Testing

Added test MemoryRegionVMACheck that verifies ELD emits a clear error when a section VMA does not fit in its
assigned memory region.

cc @parth-07 @quic-seaswara

quic-seaswara · 2026-04-26T22:26:28Z

+#START_TEST
+RUN: %clang %clangg0opts -o %t1.1.o %p/Inputs/1.c -c -ffunction-sections
+RUN: %not %link %linkopts -o %t1.1.out %t1.1.o -T %p/Inputs/script.t 2>&1 | %filecheck %s
+#CHECK: section '.foo' will not fit in region 'RAM'


There is no error with bfd linker.

quic-seaswara · 2026-04-26T22:28:37Z

+              << sec->name() << region.getName() << (secEnd - regionEnd);
+      }
+    }
+  }


With bfd, any explicit address specified, is not assigned to the memory region.

Probably the user needs to be notified, that this output section is not part of the memory region as a note, and also a linker script warning using -Wlinker-script that this section is outside the memory region bounds.

In any case these might be needed to be moved to ScriptMemoryRegion to flag.

Hi @quic-seaswara, My initial thought was also to add this check in ScriptMemoryRegion or verifyMemoryRegions(), but during debugging I found that final section addresses are not yet assigned at that point (they are still 0x0).That's why I moved the check to postLayout() where addresses are fully assigned. That's why I moved the check to postLayout() where addresses are fully assigned.

I will address suggested comments those are making more sense.

Thank You ::((

deepakshirkem · 2026-04-27T21:03:22Z

Hi @quic-seaswara,
Updated the fix as per your feedback.Moved check to ScriptMemoryRegion::verifyMemoryUsage() as you suggested Changed from error to warning under -Wlinker-script matching BFD behavior Warning runs only once after layout is complete. Please review when you get a chance.

Thank you ::((

deepakshirkem · 2026-05-06T19:36:06Z

Hi @quic-seaswara / @quic-areg, Please take another look at these changes when you get a chance?

quic-seaswara · 2026-05-06T19:53:09Z

+      uint64_t vma = out->prolog().vma().result();
+      if (!containsVMA(vma))
+        Config.raise(Diag::warn_section_not_in_region)
+            << out->name() << getName() << utility::toHex(vma);


Need the linker script file also in the warning message.

quic-seaswara · 2026-05-06T19:53:26Z

+      if (&out->epilog().region() != this)
+        continue;
+      if (!out->prolog().hasVMA())
+        continue;


You might want to move this condition to line 51 ?

quic-seaswara · 2026-05-06T19:59:13Z

+    for (auto *out : SectMap) {
+      if (!out->epilog().hasRegion())
+        continue;
+      if (&out->epilog().region() != this)


Instead of passing the sectionMap can verifyMemoryRegions run on all output sections that have memory region and call verifyMemoryUsage ? The code can be greatly simplified I think.

Note : the original loop will not change,

quic-seaswara · 2026-05-06T19:59:44Z

+#START_TEST
+RUN: %clang %clangg0opts -o %t1.1.o %p/Inputs/1.c -c -ffunction-sections
+RUN: %link %linkopts -o %t1.1.out %t1.1.o -T %p/Inputs/script.t -Wlinker-script 2>&1 | %filecheck %s
+RUN: %link %linkopts -o %t1.2.out %t1.1.o -T %p/Inputs/script.t 2>&1 | %filecheck %s --check-prefix=NOWARN --allow-empty


Why --allow-empty ?

quic-seaswara · 2026-05-06T20:00:16Z

+#---MemoryRegionVMACheck.test----------------------- Executable -----------------#
+#BEGIN_COMMENT
+# Test that ELD emits a warning when a section VMA does not fit
+# in its assigned memory region, matching BFD behavior.


Does bfd emit a warning by default ?

deepakshirkem · 2026-05-07T19:16:34Z

Hi @quic-seaswara, I apologize for the misunderstanding. I have not addressed these comments carefully enough.

There is no error with bfd linker.

With bfd, any explicit address specified, is not assigned to the memory region.

Probably the user needs to be notified, that this output section is not part of the memory region as a note, and also a linker script warning using -Wlinker-script that this section is outside the memory region bounds.

In any case these might be needed to be moved to ScriptMemoryRegion to flag.

I have re-verified the behavior both BFD and LLD error out for this test case. If you give me the go-ahead, I will implement this as an error to match BFD and LLD behavior.

ELD did not report any error when a section's explicit VMA does not fit within its assigned memory region. Both BFD and LLD error out in this case. Fix by: - Changing warn_section_not_in_region to error_section_not_in_region - Adding linker script file context to the error message - Simplifying verifyMemoryUsage to take a single OutputSectionEntry instead of SectionMap, matching LLD's checkMemoryRegion pattern - Moving the section loop to verifyMemoryRegions in GNULDBackend Fixes qualcomm#327. Signed-off-by: deepakshirkem <deepakshirke509@gmail.com>

deepakshirkem · 2026-05-08T21:29:56Z

Hi @quic-seaswara, please review the latest changes. I have matched the BFD behavior:

BFD & LLD:

ELD:

Thank You ::))

quic-seaswara requested changes Apr 26, 2026

View reviewed changes

quic-seaswara requested review from parth-07 and quic-areg April 26, 2026 22:29

deepakshirkem force-pushed the fix/memory-region-vma-check-327 branch 2 times, most recently from c171680 to 87bc13a Compare April 27, 2026 21:01

deepakshirkem requested a review from quic-seaswara April 27, 2026 21:03

quic-seaswara reviewed May 6, 2026

View reviewed changes

deepakshirkem force-pushed the fix/memory-region-vma-check-327 branch from 87bc13a to 4ece383 Compare May 8, 2026 21:24

deepakshirkem requested a review from quic-seaswara May 8, 2026 21:31

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

[memory-region] Error when section VMA does not fit in region#1102

[memory-region] Error when section VMA does not fit in region#1102
deepakshirkem wants to merge 1 commit intoqualcomm:mainfrom
deepakshirkem:fix/memory-region-vma-check-327

deepakshirkem commented Apr 25, 2026

Uh oh!

quic-seaswara Apr 26, 2026

Uh oh!

quic-seaswara Apr 26, 2026

Uh oh!

deepakshirkem Apr 27, 2026 •

edited

Loading

Uh oh!

deepakshirkem commented Apr 27, 2026

Uh oh!

deepakshirkem commented May 6, 2026

Uh oh!

quic-seaswara May 6, 2026

Uh oh!

quic-seaswara May 6, 2026

Uh oh!

quic-seaswara May 6, 2026

Uh oh!

quic-seaswara May 6, 2026

Uh oh!

quic-seaswara May 6, 2026

Uh oh!

deepakshirkem commented May 7, 2026

Uh oh!

deepakshirkem commented May 8, 2026 •

edited

Loading

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

Conversation

deepakshirkem commented Apr 25, 2026

Problem

Fix

Testing

Uh oh!

quic-seaswara Apr 26, 2026

Choose a reason for hiding this comment

Uh oh!

quic-seaswara Apr 26, 2026

Choose a reason for hiding this comment

Uh oh!

deepakshirkem Apr 27, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

deepakshirkem commented Apr 27, 2026

Uh oh!

deepakshirkem commented May 6, 2026

Uh oh!

quic-seaswara May 6, 2026

Choose a reason for hiding this comment

Uh oh!

quic-seaswara May 6, 2026

Choose a reason for hiding this comment

Uh oh!

quic-seaswara May 6, 2026

Choose a reason for hiding this comment

Uh oh!

quic-seaswara May 6, 2026

Choose a reason for hiding this comment

Uh oh!

quic-seaswara May 6, 2026

Choose a reason for hiding this comment

Uh oh!

deepakshirkem commented May 7, 2026

Uh oh!

deepakshirkem commented May 8, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

deepakshirkem Apr 27, 2026 •

edited

Loading

deepakshirkem commented May 8, 2026 •

edited

Loading