Bug 8916

Summary:	LDFLAGS pass to openssh
Product:	buildroot	Reporter:	Timur Mustafin <yxygyxyg>
Component:	Other	Assignee:	unassigned
Status:	RESOLVED WORKSFORME
Severity:	normal	CC:	buildroot
Priority:	P5
Version:	unspecified
Target Milestone:	---
Hardware:	Other
OS:	Linux
Host:		Target:
Build:

Description Timur Mustafin 2016-05-10 16:40:18 UTC

The fail message we obtain in buildroot-compiled chroot environment:

bash-4.3# ssh
bash: /usr/bin/ssh: No such file or directory

It happens because ssh execute file does not contain proper dynamic linker way:

# readelf /tmp/usr/bin/ssh -l
...
[Requesting program interpreter: /home/cf/e2k/mcst.rel-21-0.fs/2016-04-12/e2k-generic-linux.cross/lib64/ld-linux.so.2]
...

The proper way to dynamic linker we set with BR2_TARGET_LDFLAGS="-Wl,-dynamic-linker,/lib/ld-linux.so.2" option in .config file. This scheme works fine in different packages (busybox, bash ...).
In case of openssh package the option does not pass through package/openssh/openssh.mk file:

...
OPENSSH_CONF_ENV = LD="$(TARGET_CC)" LDFLAGS="$(TARGET_CFLAGS)"
...

Here internal openssh option LDFLAGS contain only common $(TARGET_CFLAGS). Common $(TARGET_LDFLAGS) does not pass inside openssh build system here.

If we change this line to the next:

...
OPENSSH_CONF_ENV = LD="$(TARGET_CC)" LDFLAGS="$(TARGET_CFLAGS) $(TARGET_LDFLAGS)"
...

ssh works fine.

Comment 1 Thomas Petazzoni 2016-09-12 15:44:05 UTC

It works just fine here, and there is absolutely no need to pass custom LDFLAGS for this to work. The default dynamic linker path is set by the cross-compiler and is correct.

I've just tested the following Buildroot defconfig:

BR2_x86_64=y
BR2_x86_core2=y
BR2_TOOLCHAIN_EXTERNAL=y
BR2_PACKAGE_OPENSSH=y

ssh has the correct dynamic linker path:

 readelf -a output/target/usr/bin/ssh | grep -i interpreter
      [Requesting program interpreter: /lib64/ld-linux-x86-64.so.2]

and when I extract the rootfs.tar and chroot into it:

$ sudo chroot rootfs /bin/sh
/ # ssh -l
Couldn't open /dev/null: No such file or directory
/ # mount -t devtmpfs none /dev
/ # ssh -l
option requires an argument -- l
usage: ssh [-1246AaCfGgKkMNnqsTtVvXxYy] [-b bind_address] [-c cipher_spec]
           [-D [bind_address:]port] [-E log_file] [-e escape_char]
           [-F configfile] [-I pkcs11] [-i identity_file]
           [-J [user@]host[:port]] [-L address] [-l login_name] [-m mac_spec]
           [-O ctl_cmd] [-o option] [-p port] [-Q query_option] [-R address]
           [-S ctl_path] [-W host:port] [-w local_tun[:remote_tun]]
           [user@]hostname [command]

So I think you have something in your environment that causes the cross-compiler to encode a wrong path to the dynamic linker.

Comment 2 Timur Mustafin 2016-09-16 13:28:44 UTC

I thought that BR2_TARGET_LDFLAGS option should be pass to the linker when building any package. As it is mentioned in menuconfig's help:
"BR2_TARGET_LDFLAGS:
Extra options to pass to the linker when building for the target.".
In case of openssh package the option is not passed to the linker.