Using a 32bit libray in ArmV8 applicatio

Hello Sir,
We are using the liaro's aarch64-linux-gnu-gcc compiler, (version = gcc-linaro-6.3.1-2017.02-x86_64_aarch64-linux-gnu) for cross compiling for armv8, Cortex A53. We use many libraries, one of them is openssl-1.0.1p which supports max till armv7. I tried compiling this library using the command "aarch64-linux-gnu-gcc -march=armv7-a". It gives the error as "error: unknown value ‘armv7-a’ for -march"
(But the man page of aarch64-linux-gnu-gcc says these are supported "armv7, armv7-a, armv7-m, armv7-r, armv7e-m, armv7ve")
How do I compile this libray ?

I tried compiling the openssl-1.0.1p library with the 32 bit compiler armv8l-linux-gnueabihf-gcc (version = gcc-linaro-6.3.1-2017.02-x86_64_armv8l-linux-gnueabihf) using -march=armv7-a, since it supports it.
It compiles. But when linking with the application, I get the linker error as "incompatible library"

How do I solve this issue on armv8