From b8d59bec22a31e3faafc77db97dc7fa8fa79fa15 Mon Sep 17 00:00:00 2001 From: "Yann E. MORIN" Date: Sun, 22 Jan 2023 10:09:47 +0100 Subject: [PATCH] Makefile: fix build when $(O) ends in _defconfig Commit e6195c53041f (Makefile: fix use of many br2-external trees) fixed a slowdown with many br2-external trees. In doing so, it changed the type of the %_defconfig rule: the stem is no longer present in the prerequisites, so it changes from a pattern rule to an implicit pattern rule [0]. It is not unusual to name the build directory after the defconfig that is being built, so we may end up with a build directory named meh_defconfig. Before e6195c53041f, the pattern rule would not match [1], but now it does, which causes somewhat-cryptic build failures: Makefile:1015: *** "Can't find /some/path/meh_defconfig". Stop. The issue is that we have this set of rules and assignments (elided and reordered for legibility): all: world world: target-post-image target-post-image: staging-finalize staging-finalize: $(STAGING_DIR_SYMLINK) $(STAGING_DIR_SYMLINK): | $(BASE_DIR) BASE_DIR := $(CANONICAL_O) CANONICAL_O := $(shell mkdir -p $(O) >/dev/null 2>&1)$(realpath $(O)) So, there is a rule that (eventually) has a dependency on $(O), but we have no rule that provides it explicitly, so the %_defconfig rule kicks in, with the stem as "/some/path/meh". When the loop searches all the ".../configs/" directories for a file named ".../configs/%_defconfig", it actually looks for a file named ".../configs//some/path/meh_defconfig" and that indeed never matches anything. The solution is to provide an actual rule for $(BASE_DIR), so that the implicit rule does not kick in. [0] Terminology and behaviour in make is hard, so the terms we used here may be wrong or incorrectly used, and/or the explanations for the behaviour be wrong or incomplete... Still, the reasoning stands, and the root cause is the removal of the stem in the RHS of the rule (adding one back does fix the issue). [1] not sure how the prerequisite was solved before e6195c53041f, though... Fixes: e6195c53041f Reported-by: Romain Naour Signed-off-by: Yann E. MORIN Cc: Nevo Hed Cc: Peter Korsgaard Tested-by: Sebastian Weyer Signed-off-by: Yann E. MORIN (cherry picked from commit 5bd2cafc326141eede4f917069ed21b6d38f88c2) Signed-off-by: Peter Korsgaard --- Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Makefile b/Makefile index 3bdc2f08c9..3828cf26ed 100644 --- a/Makefile +++ b/Makefile @@ -1044,7 +1044,7 @@ savedefconfig: $(BUILD_DIR)/buildroot-config/conf outputmakefile # staging and target directories do NOT list these as # dependencies anywhere else -$(BUILD_DIR) $(BASE_TARGET_DIR) $(HOST_DIR) $(BINARIES_DIR) $(LEGAL_INFO_DIR) $(REDIST_SOURCES_DIR_TARGET) $(REDIST_SOURCES_DIR_HOST) $(PER_PACKAGE_DIR): +$(BASE_DIR) $(BUILD_DIR) $(BASE_TARGET_DIR) $(HOST_DIR) $(BINARIES_DIR) $(LEGAL_INFO_DIR) $(REDIST_SOURCES_DIR_TARGET) $(REDIST_SOURCES_DIR_HOST) $(PER_PACKAGE_DIR): @mkdir -p $@ # outputmakefile generates a Makefile in the output directory, if using a