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

[Jan Kiszka <jan.kiszka@siemens.com>]

On 06.10.23 08:17, Hombourger, Cedric (DI SW CAS ES LI) wrote:
> On 06/10/2023 07:27, Kiszka, Jan (T CED) wrote:
>> On 06.10.23 07:03, 'cedric.hombourger@siemens.com' via isar-users wrote:
>>> 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:
>> package_arch == host_arch looks redundant here.
> 
> wouldn't dropping it make the second case from the below table pick the
> host when we really want the target?
> 
> +--------------------+--------------+--------------+-------------+-----------+---------------+-----------------------------------+-------+
> | config             | recipe       | PACKAGE_ARCH | DISTRO_ARCH |
> HOST_ARCH | sbuild-chroot | proposed check                    | eval  |
> +--------------------+--------------+--------------+-------------+-----------+---------------+-----------------------------------+-------+
> | qemuarm64-bookworm | hello-native | amd64        | arm64       |
> amd64     | host          | amd64 == amd64 and amd64 != arm64 | True  |
> +--------------------+--------------+--------------+-------------+-----------+---------------+-----------------------------------+-------+
> | qemuarm64-bookworm | hello        | arm64        | amd64       |
> amd64     | target        | arm64 == amd64 and arm64 != amd64 | False |
> +--------------------+--------------+--------------+-------------+-----------+---------------+-----------------------------------+-------+
> | qemuamd64-bookworm | hello-native | amd64        | amd64       |
> amd64     | target        | amd64 == amd64 and amd64 != amd64 | False |
> +--------------------+--------------+--------------+-------------+-----------+---------------+-----------------------------------+-------+
> | qemuamd64-bookworm | hello        | amd64        | amd64       |
> amd64     | target        | amd64 == amd64 and amd64 != amd64 | False |
> +--------------------+--------------+--------------+-------------+-----------+---------------+-----------------------------------+-------+
> 

This is missing one variable: ISAR_CROSS_COMPILE

How about this condition to decide whether to use the host build env?

if distro_arch != host_arch and \
   (package_arch == host_arch or \
    (package_arch == distro_arch and mode == "1")):
    d.setVar('BUILD_ARCH', host_arch)
    schroot_dir = d.getVar('SCHROOT_HOST_DIR', False)
    sbuild_dep = "sbuild-chroot-host" + flavor_suffix + ":do_build"
    sdk_toolchain = "crossbuild-essential-" + distro_arch
else:
    d.setVar('BUILD_ARCH', distro_arch)
    schroot_dir = d.getVar('SCHROOT_TARGET_DIR', False)
    sbuild_dep = "sbuild-chroot-target" + flavor_suffix + ":do_build"
    sdk_toolchain = "build-essential"

Jan

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