From 5c48ecedf7769f67c1e5592c1ef5202a4a967a34 Mon Sep 17 00:00:00 2001 From: Jim Cromie Date: Sat, 2 May 2026 17:32:56 -0600 Subject: [PATCH] docs/dyndbg: explain flags parse 1st When writing queries to >control, flags are parsed 1st, since they are the only required field, and they require specific compositions. So if the flags draw an error (on those specifics), then keyword errors aren't reported. This can be mildly confusing/annoying, so explain it instead. cc: linux-doc@vger.kernel.org Reviewed-by: Louis Chauvet Signed-off-by: Jim Cromie Signed-off-by: Jonathan Corbet Message-ID: <20260502-dyndbg-doc-v1-2-67cc4a93a77e@gmail.com> --- Documentation/admin-guide/dynamic-debug-howto.rst | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst index 4b14d9fd0300..9c2f096ed1d8 100644 --- a/Documentation/admin-guide/dynamic-debug-howto.rst +++ b/Documentation/admin-guide/dynamic-debug-howto.rst @@ -109,10 +109,19 @@ The match-spec's select *prdbgs* from the catalog, upon which to apply the flags-spec, all constraints are ANDed together. An absent keyword is the same as keyword "*". +Note that since the match-spec can be empty, the flags are checked 1st, +then the pairs of keyword and value. Flag errs will hide keyword errs:: -A match specification is a keyword, which selects the attribute of -the callsite to be compared, and a value to compare against. Possible -keywords are::: + bash-5.2# ddcmd mod bar +foo + dyndbg: read 13 bytes from userspace + dyndbg: query 0: "mod bar +foo" mod:* + dyndbg: unknown flag 'o' + dyndbg: flags parse failed + dyndbg: processed 1 queries, with 0 matches, 1 errs + +So a match-spec is a keyword, which selects the attribute of the +callsite to be compared, and a value to compare against. Possible +keywords are:: match-spec ::= 'func' string | 'file' string |