[U-Boot] [PATCH 1/1] net: remove superfluous __packed attribute

[Heinrich Schuchardt]

On 10/12/19 3:29 PM, Heinrich Schuchardt wrote:
> On 10/3/19 8:01 PM, Heinrich Schuchardt wrote:
>> On 10/3/19 7:09 PM, Tom Rini wrote:
>>> On Thu, Oct 03, 2019 at 07:01:22PM +0200, Heinrich Schuchardt wrote:
>>>
>>>> struct ip_udp_hdr is naturally packed. There is no point in adding a
>>>> __packed attribute. With the attribute the network stack does not
>>>> compile
>>>> using GCC 9.2.1:
>>>>
>>>> net/net.c: In function ‘net_process_received_packet’:
>>>> net/net.c:1288:23: error: taking address of packed member of ‘struct
>>>> ip_udp_hdr’ may result in an unaligned pointer value
>>>> [-Werror=address-of-packed-member]
>>>>   1288 |    sumptr = (ushort *)&(ip->udp_src);
>>>>        |                       ^~~~~~~~~~~~~~
>>>>
>>>> So let's remove the attribute.
>>>>
>>>> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
>>>> ---
>>>>   include/net.h | 2 +-
>>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/include/net.h b/include/net.h
>>>> index 75a16e4c8f..bd875b56f5 100644
>>>> --- a/include/net.h
>>>> +++ b/include/net.h
>>>> @@ -390,7 +390,7 @@ struct ip_udp_hdr {
>>>>       u16        udp_dst;    /* UDP destination port        */
>>>>       u16        udp_len;    /* Length of UDP packet        */
>>>>       u16        udp_xsum;    /* Checksum            */
>>>> -} __attribute__((packed));
>>>> +};
>>>>
>>>>   #define IP_UDP_HDR_SIZE        (sizeof(struct ip_udp_hdr))
>>>>   #define UDP_HDR_SIZE        (IP_UDP_HDR_SIZE - IP_HDR_SIZE)
>>>
>>> This came from:
>>> commit 704f3acfcf55343043bbed01c5fb0a0094a68e8a
>>> Author: Denis Pynkin <denis.pynkin at collabora.com>
>>> Date:   Fri Jul 21 19:28:42 2017 +0300
>>>
>>>      net: Use packed structures for networking
>>>
>>>      PXE boot is broken with GCC 7.1 due option '-fstore-merging'
>>> enabled
>>>      by default for '-O2':
>>>
>>>      BOOTP broadcast 1
>>>      data abort
>>>      pc : [<8ff8bb30>]          lr : [<00004f1f>]
>>>      reloc pc : [<17832b30>]    lr : [<878abf1f>]
>>>      sp : 8f558bc0  ip : 00000000     fp : 8ffef5a4
>>>      r10: 8ffed248  r9 : 8f558ee0     r8 : 8ffef594
>>>      r7 : 0000000e  r6 : 8ffed700     r5 : 00000000  r4 : 8ffed74e
>>>      r3 : 00060101  r2 : 8ffed230     r1 : 8ffed706  r0 : 00000ddd
>>>      Flags: nzcv  IRQs off  FIQs off  Mode SVC_32
>>>      Resetting CPU ...
>>>
>>>      Core reason is usage of structures for network headers without
>>> packed
>>>      attribute.
>>>
>>>      Reviewed-by: Yauheni Kaliuta <yauheni.kaliuta at redhat.com>
>>>      Signed-off-by: Denis Pynkin <denis.pynkin at collabora.com>
>>>      Acked-by: Joe Hershberger <joe.hershberger at ni.com>
>>>
>>> ... so adding a few folks to the list and lets see if patchwork picks up
>>> this tag:
>>> Fixes: 704f3acfcf55 ("net: Use packed structures for networking")
>>>
>>
>> Thanks for providing this background.
>>
>> -fstore-merging is enabled for O2 and Os. But it should not change the
>> program behavior.
>>
>> The relevant code is in gcc/gimple-ssa-store-merging.c. It has been
>> completely overhauled since GCC 7.1.
>>
>> I have seen no problems with DHCP, ping and tFTP on arm and arm64 with
>> GCC 9.2.1.
>>
>> Best regards
>>
>> Heinrich
>>
>> Since GCC 7.1 some bugs have been fixed, e.g.
>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86492
>>
>
> Hello Joe,
>
> how will we carry on, to get the issue resolved?
>
> Best regards
>
> Heinrich
> _______________________________________________

Hello Tom, hello Joe,

I still cannot build sandbox_defconfig. How will we resolve this issue?

Best regards

Heinrich