From: Jose Vasconcellos <jvasco@verizon.net>
To: Gary Thomas <gary@mlbassoc.com>
Cc: ecos-patches@ecos.sourceware.org
Subject: Re: redboot fconfig crash with gcc 4.3.2
Date: Tue, 20 Jan 2009 13:19:00 -0000 [thread overview]
Message-ID: <4975CF46.7010203@verizon.net> (raw)
In-Reply-To: <49758360.4020009@mlbassoc.com>
Gary Thomas wrote:
> Jose Vasconcellos wrote:
>> Redboot gets an exception when trying to set any IP address with fconfig
>> when using gcc-4.3.2 on an ixp425 target (armeb). The issue seems to be
>> an alignment problem as val_ptr contains an odd address; it looks
>> like gcc
>> is optimizing and trying to do a copy on a word boundary. The removal of
>> the cast fixes the problem.
>>
>>
>> --- fconfig.c 2009-01-18 14:34:11.000000000 -0500
>> +++ fconfig.c.new 2009-01-18 14:35:22.000000000 -0500
>> @@ -388,7 +388,7 @@
>> break;
>> #ifdef CYGPKG_REDBOOT_NETWORKING
>> case CONFIG_IP:
>> - memcpy(&hold_ip_val.s_addr, &((in_addr_t *)val_ptr)->s_addr,
>> sizeof(in_addr_t));
>> + memcpy(&hold_ip_val.s_addr, val_ptr, sizeof(in_addr_t));
>> if (!_gethostbyname(line, &new_ip_val)) {
>> return CONFIG_BAD;
>> }
>>
>
> Sounds like a *BUG* in the compiler. Have you reported it?
>
> This does more than remove the cast :-) What if the s_addr field is not
> at the start of the structure? I know it hasn't moved in 25+ years, but
> I don't like tossing correctness [even if only pedantic] away.
>
> Maybe there's another way to solve this. Does it happen on arm[el]?
>
This doesn't look like a compiler bug to me. I suspect that this problem
affects other arm variants but I only have access to an ixp425. The code
is incorrect as val_ptr is pointing to a place in a configuration buffer for
the raw data. Imposing (via a cast) the structure is not the right solution.
Note that a few lines down in the source, the copy in the other direction
does not have such a cast.
Jose
prev parent reply other threads:[~2009-01-20 13:19 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-19 22:23 Jose Vasconcellos
2009-01-20 7:55 ` Gary Thomas
2009-01-20 9:20 ` Daniel Néri
2009-01-20 13:19 ` Jose Vasconcellos [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4975CF46.7010203@verizon.net \
--to=jvasco@verizon.net \
--cc=ecos-patches@ecos.sourceware.org \
--cc=gary@mlbassoc.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).