Merge #21089: guix: Add support for powerpc64{,le}

95990b9f32 guix: Update conservative space requirements (Carl Dong)
5e6df11326 guix: Add support for powerpc64{,le} (Carl Dong)

Pull request description:

  ```
  The new time-machine commit contains a few small changes that make the
  powerpc cross-toolchain work.
  ```

  See this compare to review my custom patches to Guix: 7d6bd44da5...6c9d16db96

ACKs for top commit:
  fanquake:
    ACK 95990b9f32

Tree-SHA512: 464b0fb93d65962d8c27499293edb618d13d18f40d44e3eed96935e86d430666dfb1c5b8a30f99ffdfd17b44514ad88e358977390b689a2e3831d521f6f7b86a

contrib/guix/README.md

@@ -13,11 +13,9 @@ We achieve bootstrappability by using Guix as a functional package manager.
 
 Conservatively, a x86_64 machine with:
 
-- 4GB of free disk space on the partition that /gnu/store will reside in
-- 24GB of free disk space on the partition that the Bitcoin Core git repository
-  resides in
-
-> Note: these requirements are slightly less onerous than those of Gitian builds
+- 16GB of free disk space on the partition that /gnu/store will reside in
+- 8GB of free disk space per platform triple you're planning on building (see
+  the `HOSTS` environment variable description)
 
 ## Setup
 

contrib/guix/guix-build.sh

@@ -69,7 +69,7 @@ fi
 ################
 
 # Default to building for all supported HOSTs (overridable by environment)
-export HOSTS="${HOSTS:-x86_64-linux-gnu arm-linux-gnueabihf aarch64-linux-gnu riscv64-linux-gnu
+export HOSTS="${HOSTS:-x86_64-linux-gnu arm-linux-gnueabihf aarch64-linux-gnu riscv64-linux-gnu powerpc64-linux-gnu powerpc64le-linux-gnu
                        x86_64-w64-mingw32
                        x86_64-apple-darwin18}"
 
@@ -148,7 +148,7 @@ SOURCE_DATE_EPOCH="${SOURCE_DATE_EPOCH:-$(git log --format=%at -1)}"
 time-machine() {
     # shellcheck disable=SC2086
     guix time-machine --url=https://github.com/dongcarl/guix.git \
-                      --commit=7d6bd44da57926e0d4af25eba723a61c82beef98 \
+                      --commit=6c9d16db962a6f7155571b36eced681fd2889e23 \
                       --max-jobs="$MAX_JOBS" \
                       --keep-failed \
                       ${SUBSTITUTE_URLS:+--substitute-urls="$SUBSTITUTE_URLS"} \

contrib/guix/libexec/build.sh

@@ -141,6 +141,8 @@ case "$HOST" in
                 arm-linux-gnueabihf)   echo /lib/ld-linux-armhf.so.3 ;;
                 aarch64-linux-gnu)     echo /lib/ld-linux-aarch64.so.1 ;;
                 riscv64-linux-gnu)     echo /lib/ld-linux-riscv64-lp64d.so.1 ;;
+                powerpc64-linux-gnu)   echo /lib/ld64.so.1;;
+                powerpc64le-linux-gnu) echo /lib/ld64.so.2;;
                 *)                     exit 1 ;;
             esac
         )
@@ -231,6 +233,10 @@ case "$HOST" in
     *mingw*)  HOST_LDFLAGS="-Wl,--no-insert-timestamp" ;;
 esac
 
+case "$HOST" in
+    powerpc64-linux-*) HOST_LDFLAGS="${HOST_LDFLAGS} -Wl,-z,noexecstack" ;;
+esac
+
 # Make $HOST-specific native binaries from depends available in $PATH
 export PATH="${BASEPREFIX}/${HOST}/native/bin:${PATH}"
 mkdir -p "$DISTSRC"

contrib/guix/manifest.scm

@@ -233,7 +233,10 @@ chain for " target " development."))
                  (make-mingw-pthreads-cross-toolchain "x86_64-w64-mingw32")
                  (make-nsis-with-sde-support nsis-x86_64)))
           ((string-contains target "riscv64-linux-")
-           (list (make-bitcoin-cross-toolchain "riscv64-linux-gnu"
+           (list (make-bitcoin-cross-toolchain target
+                                               #:base-gcc-for-libc gcc-7)))
+          ((string-contains target "powerpc64le-linux-")
+           (list (make-bitcoin-cross-toolchain target
                                                #:base-gcc-for-libc gcc-7)))
           ((string-contains target "-linux-")
            (list (make-bitcoin-cross-toolchain target)))