[Buildroot] [PATCH 1/1] support/cmake: Explicitly set CMAKE_SYSTEM

[Peter Korsgaard]

>>>>> "Peter" == Peter Korsgaard <peter at korsgaard.com> writes:

Hi,

 >> On 2019-03-17 17:48 +0100, Frank Vanbever spake thusly:
 >>> Some packages test for CMAKE_SYSTEM explicitly.[1]
 >>> 
 >>> CMAKE_SYSTEM is comprised of CMAKE_SYSTEM_NAME and CMAKE_SYSTEM_VERSION.
 >>> It defaults to CMAKE_SYSTEM_NAME if CMAKE_SYSTEM_VERSION is not set.[2]
 >>> 
 >>> At the point CMAKE_SYSTEM_NAME is set to "Linux" CMAKE_SYSTEM is already
 >>> constructed. Setting it explicitly ensures that it is the correct value.

 >> This is because we do set CMAKE_SYSTEM_NAME twice, in fact:

 >> - first in toolchainfile.cmake, so that we tell cmake to use the
 >> "Buildroot" platform,

 >> - second, in the Buildroot.cmake platform definition itself, so that
 >> we eventually behave like the Linux platform.

 >> I haven't been able to really track down exacty _when_ CMAKE_SYSTEM is
 >> indeed set, but I believe it is done after the toolchainfile.cmake file
 >> is parsed, but before the Buildroot.cmake platofrm one is. And indeed,
 >> that becomes too late.

 >> So, I believe this change is correct, but...

 >> We also set CMAKE_SYSTEM_VERSION to 1, and so the real CMAKE_SYSTEM
 >> value should be set to Linux-1 if we were to follow the documentation to
 >> the letter.

 >> However, for Linux, the version does not matter, and in some situations
 >> may even be harmful (that was reported in one of the commits that
 >> introduce Buildroot.cmake andtoolchanfile.cmake).

 >> So:

 >> Acked-by: Yann E. MORIN <yann.morin.1998 at free.fr>

 > Thanks.

 > Committed after updating the commit message with the above description
 > from Yann, thanks.

Committed to 2019.02.x and 2019.05.x, thanks.

-- 
Bye, Peter Korsgaard