Auto merge of #1606 - msizanoen1:riscv, r=gnzlbg

Support for RISC-V 64-bit GNU/Linux

Add support for RISC-V 64-bit GNU/Linux.

Follow up to rust-lang/rust#66661.

r? @alexcrichton

ci/azure-install-rust.yml

@@ -8,7 +8,7 @@ steps:
       if command -v rustup; then
         # Uncomment when rustup on Azure is updated
         #rustup set profile minimal
-        rustup update $toolchain
+        rustup update --force $toolchain
         rustup default $toolchain
       else
         curl https://sh.rustup.rs -sSf | sh -s -- -y --default-toolchain $toolchain --profile=minimal

ci/build.sh

@@ -15,7 +15,7 @@ RUST=${TOOLCHAIN}
 echo "Testing Rust ${RUST} on ${OS}"
 
 if [ "${TOOLCHAIN}" = "nightly" ] ; then
-    cargo +nightly install cargo-xbuild -Z install-upgrade
+    cargo +nightly install cargo-xbuild
     rustup component add rust-src
 fi
 
@@ -220,6 +220,7 @@ nvptx64-nvidia-cuda \
 powerpc-unknown-linux-gnuspe \
 powerpc-unknown-netbsd \
 powerpc64-unknown-freebsd \
+riscv64gc-unknown-linux-gnu \
 riscv32imac-unknown-none-elf \
 riscv32imc-unknown-none-elf \
 sparc64-unknown-netbsd \

ci/dox.sh

@@ -19,7 +19,7 @@ if ! rustc --version | grep -E "nightly" ; then
 fi
 
 rustup component add rust-src
-cargo +nightly install cargo-xbuild -Z install-upgrade
+cargo +nightly install cargo-xbuild
 
 # List all targets that do currently build successfully:
 # shellcheck disable=SC1003

ci/semver.sh

@@ -13,7 +13,7 @@ if ! rustc --version | grep -E "nightly" ; then
     exit 1
 fi
 
-cargo +nightly install semverver -Z install-upgrade
+cargo +nightly install semverver
 
 TARGETS=
 case "${OS}" in

src/unix/linux_like/linux/gnu/b64/mod.rs

@@ -78,6 +78,9 @@ cfg_if! {
     } else if #[cfg(any(target_arch = "x86_64"))] {
         mod x86_64;
         pub use self::x86_64::*;
+    } else if #[cfg(any(target_arch = "riscv64"))] {
+        mod riscv64;
+        pub use self::riscv64::*;
     } else {
         // Unknown target_arch
     }