From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Petazzoni Date: Thu, 26 Sep 2013 17:54:05 +0200 Subject: [Buildroot] libgcc erroneously built as armv5 for arm920t(armv4t) In-Reply-To: <1380209693.38971.YahooMailNeo@web162205.mail.bf1.yahoo.com> References: <1380209693.38971.YahooMailNeo@web162205.mail.bf1.yahoo.com> Message-ID: <20130926175405.67336473@skate> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: buildroot@busybox.net Hello, On Thu, 26 Sep 2013 08:34:53 -0700 (PDT), adam hussein\(!\) wrote: > I've been building the at91rm9200ek configuration of buildroot to get > a toolchain I can use to build u-boot with some board specific > configuration. > > This is an ARM920T core chip with ARMv4T architecture??- later ARM9 > series have ARMv5TE architecture (http://en.wikipedia.org/wiki/ARM9) > > When gcc is built, or perhaps specifically libgcc only, it seems the > selection of 920t/v4 architecture gets lost and v5 is used instead. > This means that when I use it to build u-boot, I find it has the > __udivsi3 function using the illegal (to v4) instruction CLZ (count > leading zeros). > > The easiest workaround for me is to specify arm7tdmi and be done with > it, but I'd like to try contributing a proper fix if possible. > > It turns out that this issue has been around for some time: > > e.g. 2006: http://www.mail-archive.com/oe at handhelds.org/msg02024.html > e.g. 2007: > http://permalink.gmane.org/gmane.comp.lib.uclibc.buildroot/3139 e.g. > 2007: > http://web.archive.org/web/20070815094037/http://bugs.busybox.net/view.php?id=1406 > (referred to in previous link) > > and then the last link has this patch: > http://web.archive.org/web/20070815094037/http://bugs.busybox.net/file_download.php?file_id=1059&type=bug > > ...which seems not to have made it into the main repo, and no longer > applies correctly; all the locations have changed. > > > So, here follows an up-to-date version of it. I hope someone finds it > useful and avoids repeating all my 'digging about'. > > And many thanks to 'bjdooks' for the original. Interesting. First, thanks for the investigation. When you select BR2_arm920t as the ARM processor, we are already passing --with-arch=armv4t to the gcc configure. So, gcc should already avoid the use of CLZ, since ARMv4T does not support it. Have you investigated why passing the --with-cpu argument is also needed, in addition to --with-arch? Thanks! Thomas -- Thomas Petazzoni, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com