Fix : gh #130 : Use -O0 not -o0 to set optimisation level for TARGET=linux by Ulrond · Pull Request #131 · rdkcentral/ut-control

Ulrond · 2026-07-27T16:35:18Z

Fixes #130

Applies the patch supplied by @looopTools in the issue, with authorship preserved via git am.

-o0 is not an optimisation flag — lowercase -o is "write output to this file", so -o0 asks for a file named 0. The TARGET=linux default is now -O0.

CC ?= gcc -ggdb -O0 -Wall

TARGET=arm is untouched — it takes $(CC) from the SDK and never carried the flag.

Note for reviewers: this line is currently a no-op

Worth flagging while the line is under the microscope — Makefile:117 uses ?=, which GNU make defines as ifeq ($(origin CC),undefined). Make's built-in CC = cc has origin default, never undefined, so the assignment never fires:

$ cat probe.mk
CC ?= gcc -ggdb -O0 -Wall
show:
	@echo "CC=[$(CC)] origin=$(origin CC)"
$ make -f probe.mk show
CC=[cc] origin=default

So a standalone make TARGET=linux in ut-control compiles with bare cc — no -ggdb, no -Wall, no -O0 — and when driven from ut-core, CC arrives on the command line and overrides the line regardless. This PR is therefore a correctness fix with no behavioural change on its own.

The real -o0 damage came from ut-core passing CC="gcc -ggdb -o0 -Wall" down to this sub-make; that side is fixed in rdkcentral/ut-core#258.

If maintainers want the intended defaults to actually apply, the idiom that works while still honouring environment and command-line overrides is:

ifeq ($(origin CC),default)
CC := gcc -ggdb -O0 -Wall
endif

Deliberately left out of this PR — happy to raise it separately if wanted.

Verification

grep -rn '\-o0' --include=Makefile --include=*.mk --include=*.sh . returns no hits.
Standalone make TARGET=linux on this branch builds clean, and no file named 0 appears in the tree afterwards.

Second commit: a regression guard in the tests suite

The typo is two characters, but it survived because no functional test could ever have caught it — gcc accepted -o0, a later -o $@ on the same command line won, and -O0 is gcc's default. Every build stayed green. Only a static check on the build files can see it.

tests/check_makefile_flags.py is wired into the suite as check_makefile_flags and runs before build.sh, so a flag typo costs seconds rather than a full build. It walks every Makefile/*.mk/*.sh for a lowercase -o glued to an optimisation level (-o0, -os, -og, -ofast), skipping third-party trees. Comments are stripped before matching, so prose describing the typo does not trip the check.

Verified by reintroducing -o0 on top of the fix:

Mistyped optimisation flags:
Makefile:117: CC ?= gcc -ggdb -o0 -Wall ❌
Lowercase -o names an output file. Optimisation is -O.

Build files scanned under .. :: 9
Mistyped optimisation flags :: 1
make: *** [Makefile:90: check_makefile_flags] Error 1

On the fixed tree: 9 build files scanned, 0 findings.

The value assertion is deliberately left off

The script also supports asserting what a variable actually expands to via make printenv — --expect CC=-ggdb,-O0,-Wall — which is the stronger check, since it catches flags being dropped as well as mistyped. It is not wired up here, because it would fail immediately: CC ?= never fires (see above), so CC expands to bare cc. Turning it on therefore means deciding the ?= question first. The reason is recorded in a comment in tests/Makefile next to the target so the next person does not have to rediscover it.

The same script is added to ut-core in rdkcentral/ut-core#258, where the value assertion is enabled (COMPILER and UT_CONTROL_COMPILER must contain -ggdb -O0 -Wall).

-o0 was replaced with -O0 to correctly set optimisation level. This issue only happens with build target LINUX Fixes #130

github-actions · 2026-07-27T16:35:29Z

All contributors have signed the CLA ✍️ ✅
_{Posted by the CLA Assistant Lite bot.}

Copilot

Pull request overview

Updates the linux-target build defaults in ut-control’s Makefile to use the correct GCC optimization flag (-O0 instead of -o0) when setting the default CC command.

Changes:

Fixes the linux default compiler flags to use -O0 (optimization level 0) rather than -o0 (output file option).

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 ifeq ($(TARGET),linux)
-CC ?= gcc -ggdb -o0 -Wall
+CC ?= gcc -ggdb -O0 -Wall
 endif


Adds check_makefile_flags to the tests suite, run before build.sh so a flag typo is reported in seconds rather than after a full build. It walks the build files for a lowercase -o glued to an optimisation level (-o0, -os, -og). gcc accepts these silently and a later -o $@ on the same command line wins, so nothing ever fails - which is why #130 went unnoticed. Comments are stripped before matching, so prose describing the typo does not trip the check. The script also supports asserting what a variable expands to (--expect CC=-ggdb,-O0,-Wall) via make printenv. That is deliberately not wired up yet: 'CC ?=' in the top level Makefile never fires, since GNU make treats ?= as ifeq (origin CC,undefined) and the built-in CC has origin default. The Makefile records this so the expectation can be turned on once that is resolved. Verified by reintroducing -o0: the check fails, exit 1. Refs #130

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Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

kanjoe24 · 2026-08-05T14:33:25Z

+check_makefile_flags:
+	@$(ECHOE) UT [$@]
+	@$(FLAGS_SCRIPT) $(ROOT_DIR)/..


Please check this

+    try:
+        with open(path, "r", encoding="utf-8", errors="replace") as handle:
+            lines = handle.readlines()
+    except OSError as error:
+        print(f"{RED}Error: cannot read '{path}': {error}{RESET}")
+        return None


looopTools · 2026-08-03T08:18:42Z

I have read the CLA Document and I hereby sign the CLA

kanjoe24

Tests/makefile needs changes

kanjoe24 · 2026-08-05T14:33:25Z

+check_makefile_flags:
+	@$(ECHOE) UT [$@]
+	@$(FLAGS_SCRIPT) $(ROOT_DIR)/..


Please check this

kanjoe24 · 2026-08-05T14:35:48Z

 export LIB_DIR

-.PHONY: clean list build skeleton
+.PHONY: clean list build skeleton check_makefile_flags


also, the test Makefile is not building.

made these changes to make it run:

git diff diff --git a/tests/Makefile b/tests/Makefile index 5c64485..d56096f 100644 --- a/tests/Makefile +++ b/tests/Makefile @@ -73,7 +73,9 @@ export TARGET_EXEC export BUILD_DIR export LIB_DIR -.PHONY: clean list build skeleton check_makefile_flags +.PHONY: clean list build skeleton check_makefile_flags all + +all: build # Walk the build files for a lowercase -o glued to an optimisation level # (-o0, -os, -og). gcc accepts these silently and a later -o $@ on the same @@ -87,7 +89,7 @@ export LIB_DIR # that is resolved the expectation can be turned on. check_makefile_flags: @$(ECHOE) UT [$@] - @$(FLAGS_SCRIPT) $(ROOT_DIR)/.. + @python3 $(FLAGS_SCRIPT) $(ROOT_DIR)/.. build: check_makefile_flags @$(ECHOE) UT [$@]

130: Fixing using lower case o when setting optimisation level

8defc83

-o0 was replaced with -O0 to correctly set optimisation level. This issue only happens with build target LINUX Fixes #130

Copilot AI review requested due to automatic review settings July 27, 2026 16:35

Ulrond requested a review from a team as a code owner July 27, 2026 16:35

Ulrond added bug Something isn't working community-contribution Contribution from community labels Jul 27, 2026

Ulrond self-assigned this Jul 27, 2026

Ulrond requested review from bhanucbp and kanjoe24 July 27, 2026 16:35

Ulrond mentioned this pull request Jul 27, 2026

Make file wrongly attempts to set optimisation using lowercase o rdkcentral/ut-core#256

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Copilot started reviewing on behalf of Ulrond July 27, 2026 16:35 View session

Ulrond mentioned this pull request Jul 27, 2026

Make file wrongly attempts to set optimisation using lowercase o #130

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Copilot AI reviewed Jul 27, 2026

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Comment thread Makefile

Comment on lines 116 to 118

ifeq ($(TARGET),linux)

CC ?= gcc -ggdb -o0 -Wall

CC ?= gcc -ggdb -O0 -Wall

endif

Copilot AI review requested due to automatic review settings July 27, 2026 20:54

Copilot started reviewing on behalf of Ulrond July 27, 2026 20:55 View session

Copilot AI reviewed Jul 27, 2026

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kanjoe24 requested changes Aug 5, 2026

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Fix : gh #130 : Use -O0 not -o0 to set optimisation level for TARGET=linux - #131

Fix : gh #130 : Use -O0 not -o0 to set optimisation level for TARGET=linux#131
Ulrond wants to merge 2 commits into
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feature/gh130-fix-lowercase-o-optimisation-flag

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

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Note for reviewers: this line is currently a no-op

Verification

Second commit: a regression guard in the tests suite

The value assertion is deliberately left off

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Ulrond commented Jul 27, 2026 •

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