Re: [lwip-devel] memory alignment in 32bit architecture

[Piero 74]

Kieran or dhcp-code developers?

your opinion?
anyway, i will try suggested patch on monday!

message for Kieran:
i checked differeneces between lwip130 and cvs head: realy many
changes and bug fixed... for 131 version we should have all open bugs
fixed?
i'd like to have new release and start works for socket2... i want to
try to give my help!

bye
piero

2009/3/20, Grubb, Jared <address@hidden>:
> My first suggestion would be that the dhcp struct could get reordered to
> ensure that ip_addr will be properly aligned, but it appears that it already
> should be (as long as the dhcp* is properly aligned).
>
> So, I'm guessing it's the compiler being confused by the unnecessary cast.
> The compiler MIGHT be complaining about taking the address  &(__.addr) since
> this is a u32_t*, and not the cast to ip_addr*.
>
> Given:
>
> struct dhcp {
>   //....
>   struct ip_addr offered_dns_addr[DHCP_MAX_DNS]; /* DNS server addresses */
> };
>
>
> This line:
>       dns_setserver( n, (struct ip_addr
> *)(&(dhcp->offered_dns_addr[n].addr)));
> should be changed to:
>       dns_setserver( n, &(dhcp->offered_dns_addr[n]));
>
> That might fix it?
>
> Jared
>
>> -----Original Message-----
>> From: address@hidden [mailto:lwip-
>> address@hidden On Behalf Of Piero 74
>> Sent: Friday, March 20, 2009 1:09 PM
>> To: lwip-devel
>> Subject: Re: [lwip-devel] memory alignment in 32bit architecture
>>
>> my micro will generate a data abort exception.
>>
>> what solution do you suggest?
>> do you think that dns code is not well done (i want to say... portable
>> without changes)?
>>
>> piero
>>
>>
>> 2009/3/20, Bill Auerbach <address@hidden>:
>> > I'd trust the compiler on this one and say it's bad.  If it does end
>> up
>> > unaligned, you'll get either bad data or a exception trap depending
>> on what
>> > your processor does for this case.
>> >
>> > Bill
>> >
>> >>-----Original Message-----
>> >>From: address@hidden
>> >>[mailto:address@hidden On
>> >>Behalf Of Piero 74
>> >>Sent: Friday, March 20, 2009 2:46 PM
>> >>To: lwip-devel
>> >>Subject: Re: [lwip-devel] memory alignment in 32bit architecture
>> >>
>> >>Simon, as you said was my understanding.
>> >>but, why i have this warning:
>> >>
>> >>"i'm trying to use lwip in cvs head...
>> >>
>> >> i tried the compilation, and i saw in these piece of code (file
>> dhcp.c)
>> >>
>> >> #if LWIP_DNS
>> >>       dns_setserver( n, (struct ip_addr *)(&(dhcp-
>> >>>offered_dns_addr[n].addr)));
>> >> #endif /* LWIP_DNS */
>> >>
>> >> a warning like this:
>> >> Warning[Pa039]: use of address of unaligned structure member
>> >>....\lwip\src\core\dhcp.c 539
>> >>"
>> >>
>> >>bye
>> >>Piero
>> >
>> >
>> >
>> >
>> > _______________________________________________
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>> > http://lists.nongnu.org/mailman/listinfo/lwip-devel
>> >
>>
>>
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