[Buildroot] How to avoid rebuilding host-cmake

David Kessler djkessler at utexas.edu
Wed Feb 18 15:28:52 UTC 2015

Hi Ryan,

Thanks for the reply. Before posting, I looked over the documentation 
that discusses when a full rebuild is required.  Your assumption is 
mostly correct, I have been doing some light kernel development. And I 
have been utilizing buildroot's <pkg>_OVERRIDE_SRCDIR option. However, I 
have also been experimenting with many different configuration options, 
options provided by buildroot and by the linux kernel.  According to the 
buildroot documentation, a full rebuild is required when removing a 
package, and I haven't had much success with adding packages without 
doing a full rebuild.

So, I ask about rebuilding host-cmake because it takes quite a long 
time, and it doesn't seem like it needs to be rebuilt when I'm merely 
adding or removing a package.  I suppose that is a bit of an assumption 
on my part.... maybe host-cmake does indeed need to be rebuilt, 
depending on the package I've added or removed?

In any case, thanks for your suggestions.

Best Regards,
David Kessler--

On 02/17/2015 05:02 PM, Ryan Barnett wrote:
> David,
> On Tue, Feb 17, 2015 at 4:38 PM, David Kessler <djkessler at utexas.edu> wrote:
>> I am trying to reduce the amount of time it takes to rebuild the
>> linux kernel and its dependencies.  I am already using the external
>> toolchain option (toolchain was originally built using buildroot, but
>> in an external directory) so I’m not rebuilding the toolchain
>> unnecessarily. However, for some reason after doing ‘make clean’,
>> host-cmake has to be rebuilt. For my configuration host-cmake is
>> the most time consuming part of the build.
> A 'make clean' in the concept of Buildroot delete all build products
> (including build directories, host, staging and target trees, the
> images and the toolchain). Therefore, an understanding of when a full
> rebuild is necessary. Please see the following section in the manual:
> http://nightly.buildroot.org/manual.html#full-rebuild
> A per package rebuild functionality is availalbe and is described here:
> http://nightly.buildroot.org/manual.html#rebuild-pkg
> Is it fair to assume that you are trying to do kernel development?
> If so, then you should have a look at utilizing the
> <pkg>_OVERRIDE_SRCDIR functionality that Buildroot has which allows
> you to development of a package outside of Buildroot. For more
> detailed information on how to use this feature see Section 8.11.6 in
> the manual:
> http://nightly.buildroot.org/manual.html#_advanced_usage
> Lastly, you should take a look at utilizing ccache to speed up your
> builds, see Section 8.11.3 in the manual:
> http://nightly.buildroot.org/manual.html#_advanced_usage
> Thanks,
> -Ryan

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