Re: -native working as designed? target vs host sbuild-chroot

["cedric.hombourger@siemens.com" <cedric.hombourger@siemens.com>]

On 06/10/2023 06:59, Schmidt, Adriaan (T CED SES-DE) wrote:
> cedric.hombourger@siemens.com, Friday, October 6, 2023 4:50 AM:
>> Hello,
>>
>> I was wondering if handling of -native was working as designed (or if I
>> am missing something).
>>
>> Let's consider the following steps:
>>
>>       git clone -b next https://github.com/ilbers/isar
>>       . isar-init-build-env
>>       mc:qemuarm64-bookworm:hello-native
>>
>> Observe that the build constructs sbuild-chroot-target when I would have
>> expected sbuild-chroot-host. The sbuild environment for hello is indeed
>> configured to build an amd64 package while running on an arm64 userland
>> => the build of that package alone takes several minutes (on an Intel
>> Xeon 6242 and with /proc/cpuinfo listing 64 processors)
>>
>> In addition, when using Isar from master (where support for -native and
>> -compat is already there), the build fails to install build dependencies
>> for hello-native:
>>
>> |  sbuild-build-depends-main-dummy:amd64 : Depends: libc-dev:amd64 but
>> it is not installable
>> |                                          Depends: libstdc++-dev:amd64
>> but it is not installable
>>
>> This issue may also be reproduced on next with
>> 7bc68bb27f562257977bb5f701564ab08d4c5b3a (base: Fix HOST_ARCH for native
>> builds) removed. I guess I just making a note that -native may have
>> issues on master.
>>
>> My outstanding question would be: shouldn't -native use the *host*
>> sbuild-chroot? If we agree that it should then I am happy to look into this.
> Hi Cedric,
>
> Yes, you are right. The problem seems to be that when building -native,
> native.bbclass adapts PACKAGE_ARCH, but the selection of the sbuild-chroot
> (via SCHROOT_DEP in crossvars.bbclass) selects based on DISTRO_ARCH.
>
> Can you try what happens with:
>
> diff --git a/meta/classes/crossvars.bbclass b/meta/classes/crossvars.bbclass
> index df26f47f..508ba72d 100644
> --- a/meta/classes/crossvars.bbclass
> +++ b/meta/classes/crossvars.bbclass
> @@ -15,7 +15,7 @@ python __anonymous() {
>       flavor = d.getVar('SBUILD_FLAVOR')
>       flavor_suffix = ('-' + flavor) if flavor else ''
>
> -    distro_arch = d.getVar('DISTRO_ARCH')
> +    distro_arch = d.getVar('PACKAGE_ARCH')

sure - will give this is a try but I fear it won't work because the
condition mode == "0" remains True
You will find further below the changes that I am currently testing (the
hello-native use-case is now working as expected, currently running CI
tests)

>       if mode == "0" or d.getVar('HOST_ARCH') == distro_arch or distro_arch == None:
>           d.setVar('BUILD_HOST_ARCH', distro_arch)
>           schroot_dir = d.getVar('SCHROOT_TARGET_DIR', False)

My RFC changes below

diff --git a/meta/classes/crossvars.bbclass b/meta/classes/crossvars.bbclass
index df26f47..1378333 100644
--- a/meta/classes/crossvars.bbclass
+++ b/meta/classes/crossvars.bbclass
@@ -15,12 +15,24 @@ python __anonymous() {
      flavor = d.getVar('SBUILD_FLAVOR')
      flavor_suffix = ('-' + flavor) if flavor else ''

+    # get arch triplet
+    host_arch = d.getVar('HOST_ARCH')
      distro_arch = d.getVar('DISTRO_ARCH')
-    if mode == "0" or d.getVar('HOST_ARCH') == distro_arch or
distro_arch == None:
+    package_arch = d.getVar('PACKAGE_ARCH')
+
+    # -native build within a foreign-arch build? use host
+    if package_arch == host_arch and package_arch != distro_arch:
+        d.setVar('BUILD_HOST_ARCH', d.getVar('HOST_ARCH'))
+        schroot_dir = d.getVar('SCHROOT_HOST_DIR', False)
+        sbuild_dep = "sbuild-chroot-host" + flavor_suffix + ":do_build"
+        sdk_toolchain = "build-essential"
+    # not cross-compiling? use target
+    elif mode == "0" or d.getVar('HOST_ARCH') == distro_arch or
distro_arch == None:
          d.setVar('BUILD_HOST_ARCH', distro_arch)
          schroot_dir = d.getVar('SCHROOT_TARGET_DIR', False)
          sbuild_dep = "sbuild-chroot-target" + flavor_suffix + ":do_build"
          sdk_toolchain = "build-essential"
+    # cross-compiling for the foreign-arch: use host with cross toolchain
      else:
          d.setVar('BUILD_HOST_ARCH', d.getVar('HOST_ARCH'))
          schroot_dir = d.getVar('SCHROOT_HOST_DIR', False)


> Thanks,
> Adriaan
>
>> Thanks
>> Cedric
>>
>> Refs:
>>       next @ b602e36defa0abacb9ba874b4e98bc9741a006a0 kas: Fix a typo in
>> KAS_IMAGE_PREINSTALL list
>>       master @ 61086915e6c83fff22effa85cda64a2ac0c2f100 dpkg: Fix
>> internal deb import for sbuild
>>
>>
>>
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