Re: include/linux/build_bug.h:78:41: error: static assertion failed: "sizeof(struct rtw8814a_efuse) == 512"

[Geert Uytterhoeven]

Hi Ping-Ke,

On Fri, 10 Apr 2026 at 14:15, Ping-Ke Shih <pkshih@xxxxxxxxxxx> wrote:
> Bitterblue Smith <rtl8821cerfe2@xxxxxxxxx> wrote:
> > On 10/04/2026 12:25, kernel test robot wrote:
> > > tree:    https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > > head:   9a9c8ce300cd3859cc87b408ef552cd697cc2ab7
> > > commit: deb3ddeb18652118956fb581a39ac299e1ee5623 wifi: rtw88: Enable the new RTL8814AE/RTL8814AU drivers
> > > date:   1 year, 1 month ago
> > > config: arm-randconfig-001-20260410 (https://download.01.org/0day-ci/archive/20260410/202604101721.fsv5XmCX-lkp@xxxxxxxxx/config)
> > > compiler: arm-linux-gnueabi-gcc (GCC) 8.5.0
> > > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260410/202604101721.fsv5XmCX-lkp@xxxxxxxxx/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
> > > | Fixes: deb3ddeb1865 ("wifi: rtw88: Enable the new RTL8814AE/RTL8814AU drivers")
> > > | Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > > | Closes:  https://lore.kernel.org/oe-kbuild-all/202604101721.fsv5XmCX-lkp@xxxxxxxxx/
> > >
> > > All errors (new ones prefixed by >>):
> > >
> > >    In file included from include/linux/bitfield.h:10,
> > >                     from include/linux/fortify-string.h:5,
> > >                     from include/linux/string.h:389,
> > >                     from include/linux/uuid.h:11,
> > >                     from include/linux/mod_devicetable.h:14,
> > >                     from include/linux/usb.h:5,
> > >                     from drivers/net/wireless/realtek/rtw88/rtw8814a.c:5:
> > >>> include/linux/build_bug.h:78:41: error: static assertion failed: "sizeof(struct rtw8814a_efuse) == 512"
> >
> > struct rtw_2g_txpwr_idx is missing __packed. Could that be the reason
> > for the error? I don't see what else could be causing it.
> >
>
> I also found that flaw, but it isn't cause. I download cross compiler
> to build arm on my x86, and address the cause is:
>
> diff --git a/drivers/net/wireless/realtek/rtw88/rtw8814a.h b/drivers/net/wireless/realtek/rtw88/rtw8814a.h
> index c57c7c8f915e..7f2260117487 100644
> --- a/drivers/net/wireless/realtek/rtw88/rtw8814a.h
> +++ b/drivers/net/wireless/realtek/rtw88/rtw8814a.h
> @@ -51,10 +51,15 @@ struct rtw8814a_efuse {
>         union {
>                 struct rtw8814au_efuse u;
>                 struct rtw8814ae_efuse e;
> -       };
> +       } __packed;

How can that make a difference?
Both rtw8814au_efuse and rtw8814ae_efuse contain just (the same number
of) bytes, so __packed on the union should not make any difference?
Moreover, rtw8814au_efuse and rtw8814ae_efuse are already tagged with
__packed, which should also not make any difference.  Someone's been
sprinkling too many __packed all over the place?

>         u8 res5[0x122];                 /* 0xde */
>  } __packed;
>
> I will send a patch soon.
>
> Ping-Ke

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds