On Thu, 11 Mar 2021 09:34:01 +0000, David Howells said: > Valdis Klētnieks wrote: > > > What i *expected* was that multiple builds with different O= would each > > generate themselves a unique signing key and put it in their own O= directory > > and stay out of each other's way. > > Hmmm... Works for me. I use separate build dirs all the time. > > What version of the kernel are you using and what's the build command line - > in particular the full O= option? This is linux-next as of yesterday. For testing, I've been using: LANG=C make O=/tmp/arm64 V=1 ARCH=arm64 ASFLAGS='-mcpu=all' CROSS_COMPILE=/opt/aarch64/bin/aarch64-linux-gnu- certs/ and it insists on trying to make the certs in /usr/src/linux-next rather than /tmp/arm64: make -f /usr/src/linux-next/scripts/Makefile.build obj=certs \ single-build= \ need-builtin=1 need-modorder=1 scripts/extract-cert /usr/src/linux-next/"certs/signing_key.pem" certs/signing_key.x509 At main.c:142: - SSL error:0200100D:system library:fopen:Permission denied: ../crypto/bio/bss_file.c:69 - SSL error:2006D002:BIO routines:BIO_new_file:system lib: ../crypto/bio/bss_file.c:78 extract-cert: /usr/src/linux-next/certs/signing_key.pem: Permission denied make[2]: *** [/usr/src/linux-next/certs/Makefile:106: certs/signing_key.x509] Error 1 make[1]: *** [/usr/src/linux-next/Makefile:1847: certs] Error 2 make[1]: Leaving directory '/tmp/arm64' make: *** [Makefile:215: __sub-make] Error 2 Is it possible that it works for you because although you have separate build dirs, it's still able to write to the source tree?