linux-kernel - include/uapi/linux/vbox_vmmdev_types.h:254:6: warning: field u within 'struct vmmdev_hgcm_function_parameter64::(unnamed at include/uapi/linux/vbox_vmmdev_types.h:249:3)' is less aligned than 'union (unnamed union at include/uapi/linux/vbox_vmmdev

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Message-ID: <202601100754.L6nl4dGs-lkp@intel.com>
Date: Sat, 10 Jan 2026 07:50:44 +0800
From: kernel test robot <lkp@...el.com>
To: Arnd Bergmann <arnd@...db.de>
Cc: oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org,
 Hans de Goede <hdegoede@...hat.com>
Subject: include/uapi/linux/vbox_vmmdev_types.h:254:6: warning: field
 u within 'struct vmmdev_hgcm_function_parameter64::(unnamed at
 include/uapi/linux/vbox_vmmdev_types.h:249:3)' is less aligned than 'union
 (unnamed union at include/uapi/linux/vbox_vmmdev_types.h...

Hi Arnd,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   372800cb95a35a7c40a07e2e0f7de4ce6786d230
commit: c99e1e1d0850ff157f1bc16871acd2dff5a9bcc3 vbox: add HAS_IOPORT dependency
date:   11 months ago
config: arm-randconfig-r052-20260110 (https://download.01.org/0day-ci/archive/20260110/202601100754.L6nl4dGs-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260110/202601100754.L6nl4dGs-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202601100754.L6nl4dGs-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from drivers/virt/vboxguest/vboxguest_linux.c:15:
   In file included from include/linux/vbox_utils.h:8:
   include/uapi/linux/vbox_vmmdev_types.h:239:4: warning: field u within 'struct vmmdev_hgcm_function_parameter32' is less aligned than 'union (unnamed union at include/uapi/linux/vbox_vmmdev_types.h:223:2)' and is usually due to 'struct vmmdev_hgcm_function_parameter32' being packed, which can lead to unaligned accesses [-Wunaligned-access]
     239 |         } u;
         |           ^
>> include/uapi/linux/vbox_vmmdev_types.h:254:6: warning: field u within 'struct vmmdev_hgcm_function_parameter64::(unnamed at include/uapi/linux/vbox_vmmdev_types.h:249:3)' is less aligned than 'union (unnamed union at include/uapi/linux/vbox_vmmdev_types.h:251:4)' and is usually due to 'struct vmmdev_hgcm_function_parameter64::(unnamed at include/uapi/linux/vbox_vmmdev_types.h:249:3)' being packed, which can lead to unaligned accesses [-Wunaligned-access]
     254 |                         } u;
         |                           ^
   2 warnings generated.


vim +254 include/uapi/linux/vbox_vmmdev_types.h

f6ddd094f57934 Hans de Goede 2017-11-30  242  
f6ddd094f57934 Hans de Goede 2017-11-30  243  /** HGCM function parameter, 64-bit client. */
f6ddd094f57934 Hans de Goede 2017-11-30  244  struct vmmdev_hgcm_function_parameter64 {
f6ddd094f57934 Hans de Goede 2017-11-30  245  	enum vmmdev_hgcm_function_parameter_type type;
f6ddd094f57934 Hans de Goede 2017-11-30  246  	union {
f6ddd094f57934 Hans de Goede 2017-11-30  247  		__u32 value32;
f6ddd094f57934 Hans de Goede 2017-11-30  248  		__u64 value64;
f6ddd094f57934 Hans de Goede 2017-11-30  249  		struct {
f6ddd094f57934 Hans de Goede 2017-11-30  250  			__u32 size;
f6ddd094f57934 Hans de Goede 2017-11-30  251  			union {
f6ddd094f57934 Hans de Goede 2017-11-30  252  				__u64 phys_addr;
f6ddd094f57934 Hans de Goede 2017-11-30  253  				__u64 linear_addr;
f6ddd094f57934 Hans de Goede 2017-11-30 @254  			} u;
f6ddd094f57934 Hans de Goede 2017-11-30  255  		} __packed pointer;
f6ddd094f57934 Hans de Goede 2017-11-30  256  		struct {
f6ddd094f57934 Hans de Goede 2017-11-30  257  			/** Size of the buffer described by the page list. */
f6ddd094f57934 Hans de Goede 2017-11-30  258  			__u32 size;
f6ddd094f57934 Hans de Goede 2017-11-30  259  			/** Relative to the request header. */
f6ddd094f57934 Hans de Goede 2017-11-30  260  			__u32 offset;
f6ddd094f57934 Hans de Goede 2017-11-30  261  		} page_list;
f6ddd094f57934 Hans de Goede 2017-11-30  262  	} __packed u;
f6ddd094f57934 Hans de Goede 2017-11-30  263  } __packed;
f6ddd094f57934 Hans de Goede 2017-11-30  264  VMMDEV_ASSERT_SIZE(vmmdev_hgcm_function_parameter64, 4 + 12);
f6ddd094f57934 Hans de Goede 2017-11-30  265  

:::::: The code at line 254 was first introduced by commit
:::::: f6ddd094f5793447d594aa9f42032a7aba12b4d2 virt: Add vboxguest driver for Virtual Box Guest integration UAPI

:::::: TO: Hans de Goede <hdegoede@...hat.com>
:::::: CC: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki