kernel/linux.git/scripts/kconfig/expr.c, branch v7.3-rc1

kconfig: fix submenu rendering of negative dependencies

2026-08-14T19:33:20+00:00

The Kconfig frontend should render options that depend on a previous option in the submenu of that previous option. But currently, this breaks for negative dependencies. For example, option FOO may be rendered in the submenu of option BAR, despite FOO actually depending on !BAR. Let's fix this ironic rendering by modifying Kconfig to explicitly check negative dependencies. I've only tested locally on x86, but as far as I can tell, this only changes how 2 options are rendered in the menu: 1. NTFS3_FS, no longer in the NTFS_FS submenu, and 2. MTD_BLOCK_RO, no longer in the MTD_BLOCK submenu. Tested-by: Nathan Chancellor Reported-by: Xi Ruoyao Closes: https://lore.kernel.org/all/cbe95c15d2760f6fce8eaf207c969ce8fd3703aa.camel@xry111.site/ Assisted-by: Claude:claude-4.8-opus Signed-off-by: Julian Braha Link: https://patch.msgid.link/20260801145238.2140291-1-julianbraha@gmail.com Reviewed-by: Nicolas Schier Tested-by: Nicolas Schier Signed-off-by: Nicolas Schier

kconfig: clear expr::val_is_valid when allocated

2024-10-01T08:05:30+00:00

Since commit 95573cac25c6 ("kconfig: cache expression values"), xconfig emits a lot of false-positive "unmet direct dependencies" warnings. While conf_read() clears val_is_valid flags, 'make xconfig' calculates symbol values even before the conf_read() call. This is another issue that should be addressed separately, but it has revealed that the val_is_valid field is not initialized. Fixes: 95573cac25c6 ("kconfig: cache expression values") Signed-off-by: Masahiro Yamada

kconfig: cache expression values

2024-09-20T00:21:53+00:00

Cache expression values to avoid recalculating them repeatedly. Signed-off-by: Masahiro Yamada

kconfig: use hash table to reuse expressions

2024-09-20T00:21:52+00:00

Currently, every expression in Kconfig files produces a new abstract syntax tree (AST), even if it is identical to a previously encountered one. Consider the following code: config FOO bool "FOO" depends on (A || B) && C config BAR bool "BAR" depends on (A || B) && C config BAZ bool "BAZ" depends on A || B The "depends on" lines are similar, but currently a separate AST is allocated for each one. The current data structure looks like this: FOO->dep ==> AND BAR->dep ==> AND BAZ->dep ==> OR / \ / \ / \ OR C OR C A B / \ / \ A B A B This is redundant; FOO->dep and BAR->dep have identical ASTs but different memory instances. We can optimize this; FOO->dep and BAR->dep can share the same AST, and BAZ->dep can reference its sub tree. The optimized data structure looks like this: FOO->dep, BAR->dep ==> AND / \ BAZ->dep ==> OR C / \ A B This commit introduces a hash table to keep track of allocated expressions. If an identical expression is found, it is reused. This does not necessarily result in memory savings, as menu_finalize() transforms expressions without freeing up stale ones. This will be addressed later. One optimization that can be easily implemented is caching the expression's value. Once FOO's dependency, (A || B) && C, is calculated, it can be cached, eliminating the need to recalculate it for BAR. This commit also reverts commit e983b7b17ad1 ("kconfig/menu.c: fix multiple references to expressions in menu_add_prop()"). Signed-off-by: Masahiro Yamada

kconfig: refactor expr_eliminate_dups()

2024-09-20T00:21:52+00:00

Currently, expr_eliminate_dups() passes two identical pointers down to expr_eliminate_dups1(), which later skips processing identical leaves. This approach is somewhat tricky and, more importantly, it will not work with the refactoring made in the next commit. This commit slightly changes the recursion logic; it deduplicates both the left and right arms, and then passes them to expr_eliminate_dups1(). expr_eliminate_dups() should produce the same result. Signed-off-by: Masahiro Yamada

kconfig: add comments to expression transformations

2024-09-20T00:21:52+00:00

Provide explanations for complex transformations. Signed-off-by: Masahiro Yamada

kconfig: change some expr_*() functions to bool

2024-09-20T00:21:52+00:00

This clarifies the behavior of these functions. Signed-off-by: Masahiro Yamada

kbuild: split x*alloc() functions in kconfig to scripts/include/xalloc.h

2024-09-01T11:34:48+00:00

These functions will be useful for other host programs. Signed-off-by: Masahiro Yamada

kconfig: remove 'e1' and 'e2' macros from expression deduplication

2024-07-20T04:34:18+00:00

I do not think the macros 'e1' and 'e2' are readable. The statement: e1 = expr_alloc_symbol(...); affects the caller's variable, but this is not sufficiently clear from the code. Remove the macros. No functional change intended. Signed-off-by: Masahiro Yamada

kconfig: add const qualifiers to several function arguments

2024-07-16T07:07:14+00:00

Clarify that the given structures are not modified. Signed-off-by: Masahiro Yamada