Merge "Add README_riscv64.md with instructions how to update riscv64 prebuilts." into main am: 4399e01d8d
Original change: https://android-review.googlesource.com/c/platform/prebuilts/runtime/+/2664816
Change-Id: I1f2b0f9cc0e6a2812e9b96522d6200889eb81610
Signed-off-by: Automerger Merge Worker <[email protected]>
diff --git a/mainline/README_riscv64.md b/mainline/README_riscv64.md
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+Unlike other architectures, riscv64 is not supported by mainline yet
+(see b/286551985#comment6 for reasons why). Therefore we have to follow a
+semi-manual update process described below.
+
+This is not a fully correct process, as the prebuilts are taken from an
+arbitrary local build, and only for riscv64. Common architecture-independent
+parts of the SDKs such as headers are not updated, as that would affect
+architectures other than riscv64. One can only hope they did not diverge too
+much from the previous update.
+
+For conscrypt and statsd, we (the ART team) don't have the ownership to commit
+the updates in their proper repositories, prebuilts/module_sdk/conscrypt and
+prebuilts/module_sdk/StatsD. Therefore as a temporary workaround these prebuilts
+are committed in prebuilts/runtime/mainline/local_riscv64. Before the build
+starts, they are copied to their proper places by the art/tools/buildbot-*.sh
+scripts.
+
+To update:
+
+1. On aosp/main (full manifest):
+
+- Build apexes:
+ ```
+ $ banchan \
+ com.android.runtime \
+ com.android.tzdata \
+ com.android.os.statsd \
+ com.android.conscrypt \
+ com.android.i18n \
+ riscv64 \
+ && DIST_DIR=out/dist/mainline_modules_riscv64 m dist
+ ```
+
+- Build implementation libs:
+ ```
+ $ lunch aosp_riscv64-userdebug
+ $ m dist
+ ```
+
+- Build module SDKs:
+
+ First, cherry-pick https://r.android.com/2647900.
+ ```
+ $ TARGET_BUILD_APPS="\
+ com.android.os.statsd \
+ com.android.runtime \
+ com.android.i18n \
+ com.android.conscrypt \
+ com.android.tzdata" \
+ packages/modules/common/build/mainline_modules_sdks.sh \
+ --build-release latest \
+ --build-platform-sdks-for-mainline
+ ```
+
+2. On master-art branch (reduced manifest):
+
+- Run:
+ ```
+ $ prebuilts/runtime/mainline/update.py \
+ --local-dist-riscv64 <root-of-aosp-tree>/out/dist
+ ```
+
+- Manually inspect the updated Android.bp files and revert any sections not
+ related to riscv64 (it may be necessary to revert the entire file). Then try
+ to build with `lunch riscv64 && art/tools/buildbot-build.sh`, you may find
+ that further tweaking is needed. Make sure that the build succeeds.
+
+- Update the commit (use `lunch riscv64 && art/tools/buildbot-build.sh` as a
+ validation step in commit message). Be sure to set mast@ as reviewer.
