1) __riscv_float_abi_single is not in the provided preprocessor namespace.
The default build sets -Werror and has -Warn implicitly. Testing something
that's not defined with an #if is therefore an error.
This is possibly a behavior change. If your builds ever define that AND
set it to 0, this way will fail, but #if defined (foo) + #if foo is akward
and probably not what you intended.
2) "csrw mtvt, t0" is not legal in at least
GNU assembler (GNU Binutils) 2.35
Fortunately, riscv_encoding.h #defines a perfectly lovely value of
$0x307 that's appropriate for the chips AND is compatible with more assemblers.
This appears to be an extension in
GNU assembler (SiFive Binutils 2.32.0-2019.08.0) 2.32
(present in bl_io_sdk, as provided by SiFive)
and that's probably what's in your $PATH, but not relying on vendor
extension in this case is dead easy.
Two distinct problems. No, I'm not making different pull requests.
...this is a lot of words for a two line change. :-)
