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From:   James Bottomley <James.Bottomley@HansenPartnership.com>
To:     linux-kbuild@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org,
        Masahiro Yamada <masahiroy@kernel.org>
Subject: [PATCH 0/1] Add explicit error for missing CONFIG_ASN1
Date:   Tue, 22 Sep 2020 08:53:40 -0700
Message-Id: <20200922155341.17906-1-James.Bottomley@HansenPartnership.com>
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I recently ran into this as an error from 0day.  On x86 it's pretty
much impossible to build a configuration where CONFIG_ASN1 isn't set,
so you rarely notice a problem using the ASN.1 compiler because
something else has selected it.  However, this compiler is never built
if CONFIG_ASN1 isn't set and the error you get from kbuild is
particularly unhelpful:

   make[4]: *** No rule to make target 'security/keys/trusted-keys/tpm2key.asn1.o', needed by 'security/keys/trusted-keys/built-in.a'.
   make[4]: *** [scripts/Makefile.build:283: security/keys/trusted-keys/trusted_tpm2.o] Error 1
   make[4]: Target '__build' not remade because of errors.

This patch changes the above error to the much easier to diagnose:

   scripts/Makefile.build:387: *** CONFIG_ASN1 must be defined for the asn1_compiler.  Stop.
   make[3]: *** [scripts/Makefile.build:505: security/keys/trusted-keys] Error 2

James

---

James Bottomley (1):
  Makefile.build: Add an explicit error for missing ASN.1 compiler

 scripts/Makefile.build | 5 +++++
 1 file changed, 5 insertions(+)

-- 
2.26.2