[fedora-arm] kernel build on fc19 aarch64 model

[Richard W.M. Jones]

On Thu, Jan 02, 2014 at 04:37:45PM +0530, Sandeepa Prabhu wrote:
> Hi,
> 
> I am trying to build kernel on fc19 aarch64 image based on v8 Foundation model.
> kernel branch is based on "armv8-uefi-v3.13rc" and toolchain: gcc
> version 4.8.1 20130920 (Red Hat 4.8.1-10) (GCC)   - using 8GB RAM.
> 
> Kernel build is taking for me more than 12 hours, and adding more
> threads (-j6 etc) does not improve the build speed. Is this expected ?

Yes :-(

> or is there a step to improve kernel build?

qemu-arm64 userspace emulation[1] is a little bit faster than the
Foundation Model, but (a) it's limited to userspace emulation (fine
for compiling things) and (b) it's still damn slow.  It will still
take you hours to compile this way.

So ... cross-compiling, assuming you just want to build the kernel and
don't want to build an RPM.  On your fast x86-64 host, install
gcc-aarch64-linux-gnu and do something like this:

  make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu-

Rich.

[1] http://rwmj.wordpress.com/2013/12/22/how-to-run-aarch64-binaries-on-an-x86-64-host-using-qemu-userspace-emulation/#content

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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