From: Thomas Weißschuh Date: Thu, 15 Jan 2026 07:35:44 +0000 (+0100) Subject: hyper-v: Mark inner union in hv_kvp_exchg_msg_value as packed X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1e5271393d777f6159d896943b4c44c4f3ecff52;p=thirdparty%2Fkernel%2Flinux.git hyper-v: Mark inner union in hv_kvp_exchg_msg_value as packed The unpacked union within a packed struct generates alignment warnings on clang for 32-bit ARM: ./usr/include/linux/hyperv.h:361:2: error: field within 'struct hv_kvp_exchg_msg_value' is less aligned than 'union hv_kvp_exchg_msg_value::(anonymous at ./usr/include/linux/hyperv.h:361:2)' and is usually due to 'struct hv_kvp_exchg_msg_value' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access] 361 | union { | ^ With the recent changes to compile-test the UAPI headers in more cases, this warning in combination with CONFIG_WERROR breaks the build. Fix the warning. Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202512140314.DzDxpIVn-lkp@intel.com/ Reported-by: Nathan Chancellor Closes: https://lore.kernel.org/linux-kbuild/20260110-uapi-test-disable-headers-arm-clang-unaligned-access-v1-1-b7b0fa541daa@kernel.org/ Suggested-by: Arnd Bergmann Link: https://lore.kernel.org/linux-kbuild/29b2e736-d462-45b7-a0a9-85f8d8a3de56@app.fastmail.com/ Signed-off-by: Thomas Weißschuh Acked-by: Wei Liu (Microsoft) Tested-by: Nicolas Schier Reviewed-by: Nicolas Schier Acked-by: Greg Kroah-Hartman Link: https://patch.msgid.link/20260115-kbuild-alignment-vbox-v1-1-076aed1623ff@linutronix.de Signed-off-by: Nathan Chancellor --- diff --git a/include/uapi/linux/hyperv.h b/include/uapi/linux/hyperv.h index aaa502a7bff46..1749b35ab2c21 100644 --- a/include/uapi/linux/hyperv.h +++ b/include/uapi/linux/hyperv.h @@ -362,7 +362,7 @@ struct hv_kvp_exchg_msg_value { __u8 value[HV_KVP_EXCHANGE_MAX_VALUE_SIZE]; __u32 value_u32; __u64 value_u64; - }; + } __attribute__((packed)); } __attribute__((packed)); struct hv_kvp_msg_enumerate {