From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnout Vandecappelle Date: Wed, 30 Dec 2015 23:40:50 +0100 Subject: [Buildroot] sysroot In-Reply-To: References: <5683FCE8.6000206@mind.be> Message-ID: <56845D72.9080007@mind.be> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: buildroot@busybox.net On 30-12-15 19:42, Mathew Benson wrote: > First, I'm not complaining. I recently discovered Buildroot and I love it. > Kudos to the maintainers. I'm just learning it so I'm fumbling about a bit. > > I'm building a networked appliance that will run two applications. Both > applications are already written. One I wrote and maintained myself over the > past 4 years, but its 32 bit. Upgrading it to 64 bit would have a massive > impact on other projects. Its planned. Just not for a little while. The other > application is being written but requires 64 bit drivers. The drivers are not > open source, so I don't have access to the code. The CPU is a 64 bit Intel to > accommodate the 64 bit driver. If with "driver" you mean that it's in the kernel, then you don't have a problem: you can easily use a 64-bit kernel with a fully 32-bit userspace. It does mean that you can't build your kernel with buildroot, but it should be possible to just use your 32-bit cross-compiler for the kernel (remember to pass ARCH=x86_64). > I did get it almost working. I verified I can > run 32-bit applications by compiling host code, copying it over, and copying the > needed 32 bit libraries over. Obviously not the best solution. I got it to > cross compile 32 bit, with manual tweaks. I had to change several .so linker > scripts from "/lib" and "/usr/lib" to "/lib32" and "/usr/lib32", and changing > symbolic links in "/usr/lib32" from "/lib" to "/lib32". I see that buildroot is > not intended for this use case, so I'm ok with my manual work around. > > Though, I haven't quite got it to run correctly. Its either a dynamic linking > issue or just a misconfigured buildroot image. When I run my executable, I get > an error that suggests the system is interpreting the elf binary as a shell > script. I'm not sitting at that computer, so I can't copy the exact error. > Something like "error: unexpected "("". > > I did create a 32 bit and a 64 bit buildroot environment. I had merged them > into a single multilib 64 bit environment, though now I'm thinking it would just > be cleaner to keep them separate. Merging them is never going to make a real multilib environment, because executable will look for the dynamic linker in /lib/ld-linux.so.2 (for glibc). Both 64-bit and 32-bit executables look in the same place for it, so one of them is going to be wrong. What you could do is to use a real multilib toolchain (e.g. a Sourcery toolchain). Compile most of your rootfs in 64-bit, and the one application that needs to be 32-bit you compile directly with the external toolchain (bypassing hte buildroot wrapper). Then you also manually copy the 32-bit sysroot from the external toolchain to the target. Regards, Arnout -- Arnout Vandecappelle arnout at mind be Senior Embedded Software Architect +32-16-286500 Essensium/Mind http://www.mind.be G.Geenslaan 9, 3001 Leuven, Belgium BE 872 984 063 RPR Leuven LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle GPG fingerprint: 7493 020B C7E3 8618 8DEC 222C 82EB F404 F9AC 0DDF