Live apphost not being used by crossgen2 with source build

[ayakael]

Description

.NET 7 in source-build does not currently use NativeAOT. Thus, when building Crossgen2 from source on platforms without apphost in nuget feeds, build of runtime fails with:

/var/build/dotnet7/testing/dotnet7-stage0/src/bootstrap/sdk/7.0.100/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.Sdk.FrameworkReferenceResolution.targets(135,5): error NETSDK1084: There is no application host available for the specified RuntimeIdentifier 'linux-musl-x86'. [/var/build/dotnet7/testing/dotnet7-stage0/src/dotnet-e6dd91c290b808f971a1ac69c2fb29395bbf1051/src/runtime/src/coreclr/tools/aot/crossgen2/crossgen2.csproj]

Reproduction Steps

Crossbuild from x64 to x86, crossgen2 build will fail.

Expected behavior

Crossgen2 should be able to use to live apphost built previously by runtime

Actual behavior

Build fails due to no apphost for that RID

Regression?

Per #7335 and #66866, there was a time when this was a non-issue. With move to NativeAOT, UseLiveBuiltDotNetHost was dropped, and this use-case seems to have been removed.

Known Workarounds

None for now. I attempted to build runtime in two steps, to no avail:

ROOTFS_DIR="$CBUILDROOT" ./build.sh $args -subset Clr.Native+Host.Native
ROOTFS_DIR="$CBUILDROOT" ./build.sh $args /p:AppHostSourcePath="$builddir"/src/runtime/artifacts/obj/linux-musl-$_dotnet_target.Release/apphost/standalone/apphost

Configuration

.NET 7.0.100-rtm.22519.39
Alpine Linux Edge
x64 to x86 crossbuild

Other information

No response

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[am11]

@agocke might be able to help but AFAIK, these days crossgen2 uses live build of ilc (NativeAOT) when available or fallback to live build of corehost on platforms where NativeAOT is not available. The use of prebuilt host (from nuget package) was completely removed. Looks like you are seeing a different behavior on x86; something is still expecting prebuilt host. Perhaps we are (unintentionally) skipping live build host on x86?

Could you try git clean -xdf && ./build.sh clr+host+libs+packs just to be sure?

[ayakael]

Building just those subsets gives the same result.

[am11]

In 9a3626e, MicrosoftNETCoreDotNetHostVersion etc. were removed so no prebuilt apphost get restored. crossgen2 is published as a single-file using the live corehost build (when NativeAOT is not supported).

Maybe this patch will help:

--- a/src/coreclr/tools/aot/crossgen2/crossgen2.csproj
+++ b/src/coreclr/tools/aot/crossgen2/crossgen2.csproj
@@ -9,7 +9,7 @@
     <!-- Trimming is not currently working, but set the appropriate feature flags for NativeAOT -->
     <PublishTrimmed Condition="'$(NativeAotSupported)' == 'true'">true</PublishTrimmed>
     <RuntimeIdentifiers Condition="'$(RunningPublish)' != 'true' and '$(DotNetBuildFromSource)' != 'true'">linux-x64;linux-musl-x64;linux-arm;linux-musl-arm;linux-arm64;linux-musl-arm64;freebsd-x64;osx-x64;osx-arm64;win-x64;win-x86;win-arm64;win-arm</RuntimeIdentifiers>
-    <RuntimeIdentifiers Condition="'$(DotNetBuildFromSource)' == 'true'">$(PackageRID)</RuntimeIdentifiers>
+    <RuntimeIdentifiers Condition="'$(RunningPublish)' != 'true' and '$(DotNetBuildFromSource)' == 'true'">$(PackageRID)</RuntimeIdentifiers>
     <SelfContained>false</SelfContained>
     <SelfContained Condition="'$(RunningPublish)' == 'true'">true</SelfContained>
   </PropertyGroup>

[agocke]

This seems like it's specific to linux x86, right? I don't see any source build problems for other architectures.

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Issue Details

---

Description

.NET 7 in source-build does not currently use NativeAOT. Thus, when building Crossgen2 from source on platforms without apphost in nuget feeds, build of runtime fails with:

/var/build/dotnet7/testing/dotnet7-stage0/src/bootstrap/sdk/7.0.100/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.Sdk.FrameworkReferenceResolution.targets(135,5): error NETSDK1084: There is no application host available for the specified RuntimeIdentifier 'linux-musl-x86'. [/var/build/dotnet7/testing/dotnet7-stage0/src/dotnet-e6dd91c290b808f971a1ac69c2fb29395bbf1051/src/runtime/src/coreclr/tools/aot/crossgen2/crossgen2.csproj]

Reproduction Steps

Crossbuild from x64 to x86, crossgen2 build will fail.

Expected behavior

Crossgen2 should be able to use to live apphost built previously by runtime

Actual behavior

Build fails due to no apphost for that RID

Regression?

Per #7335 and #66866, there was a time when this was a non-issue. With move to NativeAOT, UseLiveBuiltDotNetHost was dropped, and this use-case seems to have been removed.

Known Workarounds

None for now. I attempted to build runtime in two steps, to no avail:

ROOTFS_DIR="$CBUILDROOT" ./build.sh $args -subset Clr.Native+Host.Native
ROOTFS_DIR="$CBUILDROOT" ./build.sh $args /p:AppHostSourcePath="$builddir"/src/runtime/artifacts/obj/linux-musl-$_dotnet_target.Release/apphost/standalone/apphost

Configuration

.NET 7.0.100-rtm.22519.39
Alpine Linux Edge
x64 to x86 crossbuild

Other information

No response

Author:	ayakael
Assignees:	-
Labels:	area-Infrastructure-coreclr
Milestone:	Future

[ayakael]

This seems like it's specific to linux x86, right? I don't see any source build problems for other architectures.

Indeed. I believe this is specific to x86 as crossgen2 isn't built on other community platforms (like ppc64le and s390x) as they use mono.

In 9a3626e, MicrosoftNETCoreDotNetHostVersion etc. were removed so no prebuilt apphost get restored. crossgen2 is published as a single-file using the live corehost build (when NativeAOT is not supported).

Maybe this patch will help:

--- a/src/coreclr/tools/aot/crossgen2/crossgen2.csproj
+++ b/src/coreclr/tools/aot/crossgen2/crossgen2.csproj
@@ -9,7 +9,7 @@
     <!-- Trimming is not currently working, but set the appropriate feature flags for NativeAOT -->
     <PublishTrimmed Condition="'$(NativeAotSupported)' == 'true'">true</PublishTrimmed>
     <RuntimeIdentifiers Condition="'$(RunningPublish)' != 'true' and '$(DotNetBuildFromSource)' != 'true'">linux-x64;linux-musl-x64;linux-arm;linux-musl-arm;linux-arm64;linux-musl-arm64;freebsd-x64;osx-x64;osx-arm64;win-x64;win-x86;win-arm64;win-arm</RuntimeIdentifiers>
-    <RuntimeIdentifiers Condition="'$(DotNetBuildFromSource)' == 'true'">$(PackageRID)</RuntimeIdentifiers>
+    <RuntimeIdentifiers Condition="'$(RunningPublish)' != 'true' and '$(DotNetBuildFromSource)' == 'true'">$(PackageRID)</RuntimeIdentifiers>
     <SelfContained>false</SelfContained>
     <SelfContained Condition="'$(RunningPublish)' == 'true'">true</SelfContained>
   </PropertyGroup>

Unfortunately that patch didn't work. Very curious that it insists on the apphost not existing despite the apphost being built.

[ayakael]

Is there a subset for only building and packaging apphost? I'm thinking a workaround might be to build apphost, and push it to a local nuget feed via dotnet nuget push, that is then referenced by NuGet.conf for it to be pulled full the full build. -subset Clr.Native+Host.Native builds Apphost but does not package it.

[ayakael]

sigh -subset Host packages apphost, but despite that crossgen2 refuses to pull runtime.linux-musl-x86.Microsoft.NETCore.DotNetAppHost.7.0.0-rtm.22511.4.nupkg from the local NuGet feed.