Similar to the cortex-m common linker scripts, the RISC-V linker scripts
can be unified easily, requiring only the memory addresses and lengths.
This simplifies adding new RISC-V CPU's later
Allocate and initialize a thread-local block for each thread at the
top of the stack.
Set the tls base when switching to a new thread.
Add tdata/tbss linker instructions to cortex_m and risc-v scripts.
Signed-off-by: Keith Packard <keithp@keithp.com>
---
v2:
Squash fixes
v3:
Replace tabs with spaces
v4:
Add tbss to fe310 linker script
Other archs use `_sheap` and `_eheap` to mark the start and end of
the heap.
fe310 uses `_heap_start` and `_heap_end`, so platform independent
code that wants to make use of this will needlessly fail.
For compatibility with common code, name them the same on fe310.
