I can use the command bitbake fsl-image-qt5 -c populate_sdk to compile the sdk toolchain, and I've installed and verified the sdk is working successfully. However I came across to a project which require g++ compiler version 4.8, and I checked that the gcc and g++ toolchain in yocto is 5.3. How do I configure my bitbake to build a sdk of gcc/g++ toolchain of older version 4.8?
gideon@T420:/opt/fsl-imx-x11/4.1.15-2.1.0/sysroots/cortexa7hf-neon-poky-linux-gnueabi/bin$ arm-poky-linux-gnueabi-g++ --version
arm-poky-linux-gnueabi-g++ (GCC) 5.3.0
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
The toolchain is dependent on the kernel you are using on the BSP. In the case of the BSP releases the configuration is fixed to the kernel version and toolchain version listed on the release notes.
BSP release 3.10.53 does use the GCC 4.8.2 toolchain.
To get an older toolchain one option would be looking for an older BSP release that has the required toolchain. Another option would be using the Community BSP (although it does not include the Qt5 images) and configuring for an older kernel that is matched to the required toolchain.
I hope this helps!