From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
To: "crossgcc@sourceware.org" <crossgcc@sourceware.org>,
buildroot@uclibc.org <buildroot@uclibc.org>
Subject: Re: [Buildroot] Bizarre behavior of armeb toolchain
Date: Thu, 20 Jun 2013 13:52:00 -0000 [thread overview]
Message-ID: <20130620155236.45eda7ac@skate> (raw)
In-Reply-To: <20130620154130.1606594d@skate>
On Thu, 20 Jun 2013 15:41:30 +0200, Thomas Petazzoni wrote:
> (*) On ARMv7 however, the code is different whether -mbig-endian is
> passed or not, even though an "armeb-linux" compiler is supposed to
> generate big endian code by default. When no flags is passed, both the
> data *and* code are big-endian (so it's BE32 like on ARMv5), but
> passing -mbig-endian makes the thing behave properly (code is
> little-endian, data is big-endian).
Interestingly, this problem is visible when you run gcc with the -v
option, and look at the options passed to collect2.
when no options are passed to gcc (and it generates incorrect BE32
code), the options passed to collect2 are:
/home/test/outputs/armv7be/host/usr/libexec/gcc/armeb-buildroot-linux-uclibcgnueabi/4.7.3/collect2
--sysroot=/home/test/outputs/armv7be/host/usr/armeb-buildroot-linux-uclibcgnueabi/sysroot
--eh-frame-hdr
-dynamic-linker /lib/ld-uClibc.so.0
-X -m armelfb_linux_eabi -o toto
[...]
/tmp/ccJDVjCg.o
When -mbig-endian is passed to gcc, gcc then passes the following
options to collect2:
/home/test/outputs/armv7be/host/usr/libexec/gcc/armeb-buildroot-linux-uclibcgnueabi/4.7.3/collect2
--sysroot=/home/test/outputs/armv7be/host/usr/armeb-buildroot-linux-uclibcgnueabi/sysroot
--eh-frame-hdr
--be8
-dynamic-linker /lib/ld-uClibc.so.0
-X -EB -m armelfb_linux_eabi -o toto
[...]
/tmp/ccnje5oi.o
Notice how it passes -EB and more importantly --be8, which indicates to
ld that it should swap code to make it little endian again (after it
has been generated big endian by as).
Best regards,
Thomas
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
--
For unsubscribe information see http://sourceware.org/lists.html#faq
prev parent reply other threads:[~2013-06-20 13:52 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-20 13:41 Thomas Petazzoni
2013-06-20 13:49 ` [Buildroot] " Will Newton
2013-06-20 13:52 ` Thomas Petazzoni [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=20130620155236.45eda7ac@skate \
--to=thomas.petazzoni@free-electrons.com \
--cc=buildroot@uclibc.org \
--cc=crossgcc@sourceware.org \
/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).