RossBurton: Created page with "= Unknown CPU Family = == The Problem == OpenEmbedded uses the `machine` fragment of the GCC target triplet to identify the target architecture, but Meson uses the v..."

2018-07-06T13:34:03Z

Created page with "= Unknown CPU Family = == The Problem == OpenEmbedded uses the <tt>machine</tt> fragment of the GCC target triplet to identify the target architecture, but Meson uses the v..."

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= Unknown CPU Family =

== The Problem ==

OpenEmbedded uses the <tt>machine</tt> fragment of the GCC target triplet to identify the target architecture, but Meson uses the values returned by Python's <tt>platform.machine()</tt> which is based on the <tt>uname</tt> values. These don't match, so when cross-compiling we need to map the name when writing the Meson cross file. Also OpenEmbedded patches Meson to make an unknown architecture a fatal error instead of just a warning as during the build the warning won't be visible and bad CPU family setting can produce incorrect builds.

The known CPU families in Meson are listed at http://mesonbuild.com/Reference-tables.html#cpu-families.

When this mapping table isn't complete (for example, passing mipsel instead of mips) or the list in Meson needs updating (for example, new architecture) you'll get an error from Meson:

Unknown CPU family mipsel, see https://wiki.yoctoproject.org/wiki/Meson/UnknownCPU for directions

== What To Do ==

In this situation you need to know two values: the OpenEmbedded architecture name (<tt>${TARGET_ARCH}</tt>) and the Python platform name. The platform name can be obtained in either a virtual machine or on real hardware:

$ python3 -c 'import platform; print(platform.machine())'
x86_64

As a worked example, consider the little-endian MIPS case. The <tt>TARGET_ARCH</tt> for a MIPS machine in little-endian mode is <tt>mipsel</tt> but Meson doesn't consider endian changes different CPU families so they're both <tt>mips</tt>. This is already in the [http://mesonbuild.com/Reference-tables.html#cpu-families CPU Family table] so all that needs to happen is another case added to <tt>meson_cpu_family()</tt> in <tt>meson.bbclass</tt>. Please [https://bugzilla.yoctoproject.org file a bug] with this information, or ideally write a patch.

However if the problem is that you're working on an architecture that isn't in Meson's CPU Family list, then first please [https://github.com/mesonbuild/meson/issues submit a bug to Meson] to get the canonical platform name added, and then an OpenEmbedded bug if a mapping is required.

Meson/UnknownCPU - Revision history

RossBurton: Created page with "= Unknown CPU Family = == The Problem == OpenEmbedded uses the machine fragment of the GCC target triplet to identify the target architecture, but Meson uses the v..."

RossBurton: Created page with "= Unknown CPU Family = == The Problem == OpenEmbedded uses the `machine` fragment of the GCC target triplet to identify the target architecture, but Meson uses the v..."