Re: [PATCH] Wrong unpacked structure for epoll_event on qemu-or1k (openrisc user-space)

[Thomas Huth <thuth@redhat.com>]

On 19/07/2023 14.38, Luca Bonissi wrote:
> On 19/07/23 10:49, Laurent Vivier wrote:
>>
>> According to linux/glibc sourced, epoll is only packed for x86_64.
> 
> And, in recent glibc, also for i386, even it seems not necessary: even if 
> the __alignof__(long long) is 8, structures like epoll_event are only 12 
> bytes, maybe "packed" for historical reasons. Ancient i386 gcc[s] (<3.0.0) 
> have 4 bytes for __alignof__(long long).
> 
>> Perhaps the default alignment of long is not correctly defined in qemu for 
>> openrisc?
> 
> __alignof__(long long):
> - 8 bytes: all 64 bit targets + arm, hppa, mips, ppc, sparc, xtensa, x86
> - 4 bytes: microblaze, nios2, or1k, sh4
> - 2 bytes: m68k
> - 1 byte : cris
> 
> offsetof(struct epoll_event,data):
> - 8: all 64 bit targets + arm, hppa, mips, ppc, sparc, xtensa
> - 4: cris, m68k, microblaze, nios2, or1k, sh4, x86
> 
> So, epoll_event is "naturally" packed on the following targets (checked in 
> linux-user container and/or with cross-compiler):
> - cris, m68k, microblaze, nios2, or1k, sh4, x86 (32bit)
> 
>> See include/exec/user/abitypes.h to update the value.
> 
> OK, abitypes.h should be updated with the following patch (discard the 
> previous patch on syscall_defs.h):
> 
> Signed-off-by: Luca Bonissi <qemu@bonslack.org>
> ---
> 
> diff -up a/include/exec/user/abitypes.h b/include/exec/user/abitypes.h
> --- a/include/exec/user/abitypes.h    2023-03-27 15:41:42.511916232 +0200
> +++ b/include/exec/user/abitypes.h    2023-07-19 12:09:03.001687788 +0200
> @@ -15,7 +15,15 @@
>   #define ABI_LLONG_ALIGNMENT 2
>   #endif
> 
> +#ifdef TARGET_CRIS
> +#define ABI_SHORT_ALIGNMENT 1
> +#define ABI_INT_ALIGNMENT 1
> +#define ABI_LONG_ALIGNMENT 1
> +#define ABI_LLONG_ALIGNMENT 1
> +#endif
> +
> -#if (defined(TARGET_I386) && !defined(TARGET_X86_64)) || defined(TARGET_SH4)
> +#if (defined(TARGET_I386) && !defined(TARGET_X86_64)) || 
> defined(TARGET_SH4) || \
> +    defined(TARGET_OPENRISC) || defined(TARGET_NIOS2) || 
> defined(TARGET_MICROBLAZE)
>   #define ABI_LLONG_ALIGNMENT 4
>   #endif

Hi! Thanks for the patch - but could you please send this as a new patch 
mail with a proper subject and patch description, so that it could be 
applied with "git am" ? Thanks!

  Thomas