I want to use the single-precision hard-float `sqrt`

instruction as my FPU supports `sqrt`

operation, and I made some changes to Newlib:

- Create a new C file named
`ef_sqrt.c`

under`newlib/libm/machine/riscv`

. The content of the new file is

```
#include <math.h>
float
__ieee754_sqrtf(float x)
{
asm ("fsqrt.s %0, %1" : "=f" (x) : "f" (x));
return x;
}
```

- Modify the corresponding Makefile.am and Makefile.in under
`newlib/libm/machine/riscv`

to include`ef_sqrt.c`

.

When I tried to build the toolchain using riscv-none-embed-gcc-xpackļ¼I got the āimpossible constraint in āasmāā error at the inline assembly line `asm ("fsqrt.s %0, %1" : "=f" (x) : "f" (x));`

in my new file.