I need to upgrade gcc in current system from 4.3 to 5.x.
The system is using kernel 2.6.37
But as far as I know, toolchain might use different kernel headers, so there might be mismatch, Right ?
I haven't find in documentation of arm toolchain 5.1, any mention of kernel headers.
Wasn't the tool was built with known kernel headers ?
There is no connection between the compiler and kernel headers. You should be able to upgrade gcc.
The kernel doesn't use anything from the compiler such as the standard C library.
I would recommend you give it a try.