Re: [Qemu-devel] [PATCH v1 1/1] configure: Add RISC-V host support

[Michael Clark]

On Sat, Jul 28, 2018 at 11:49 AM, Alistair Francis <address@hidden
> wrote:

> Allow QEMU to be built to run on a RISC-V host.
>
> QEMU does not yet have a RISC-V TCG or user mode target port, but
> running other architectures on RISC-V using TCI does work.
>

There is this RISC-V TCG backend here:

https://github.com/riscv/riscv-qemu/tree/wip-riscv-tcg-backend

I realized I had not sent an update to the list. There is a working TCG
backend for RISC-V:

- I've so far tested it with user-mode translation only.
- It does not support large guests e.g. 64-bit hosts on riscv32.
- The softmmu implementation is there but needs testing.
- Some things are missing, e.g. memory fences. big-endian support

You might find some other relevant changes in the configure hunks in the
patch. IIRC there were a few changes to configure, one of them was to get
the riscv disassembler working.

Signed-off-by: Alistair Francis <address@hidden>
> ---
>  configure | 18 +++++++++++++++++-
>  1 file changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/configure b/configure
> index 2a7796ea80..c3ff3ae146 100755
> --- a/configure
> +++ b/configure
> @@ -606,6 +606,16 @@ EOF
>    compile_object
>  }
>
> +check_define_value() {
> +cat > $TMPC <<EOF
> +#if (($1) != ($2))
> +#error $1 != ($2)
> +#endif
> +int main(void) { return 0; }
> +EOF
> +  compile_object
> +}
> +
>  check_include() {
>  cat > $TMPC <<EOF
>  #include <$1>
> @@ -704,6 +714,12 @@ elif check_define __arm__ ; then
>    cpu="arm"
>  elif check_define __aarch64__ ; then
>    cpu="aarch64"
> +elif check_define __riscv ; then
> +  if check_define_value __riscv_xlen 64 ; then
> +    cpu="riscv64"
> +  else
> +    cpu="riscv32"
> +  fi
>  else
>    cpu=$(uname -m)
>  fi
> @@ -712,7 +728,7 @@ ARCH=
>  # Normalise host CPU name and set ARCH.
>  # Note that this case should only have supported host CPUs, not guests.
>  case "$cpu" in
> -  ppc|ppc64|s390|s390x|sparc64|x32)
> +  ppc|ppc64|s390|s390x|sparc64|x32|riscv32|riscv64)
>      cpu="$cpu"
>      supported_cpu="yes"
>      eval "cross_cc_${cpu}=\$host_cc"
> --
> 2.17.1
>
>