[Buildroot] UPX - compression of fs at target

[Buildroot] UPX - compression of fs at target

[a]

HI, 
How can I make use of UPX so that the final image, that buildroot builds,
has libraries that are compresses even further by upx before creating the
image so that the image size get reduced further.



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[Buildroot] UPX - compression of fs at target

[Arnout Vandecappelle]

On 03/12/2019 10:32, a wrote:
> HI, 
> How can I make use of UPX so that the final image, that buildroot builds,
> has libraries that are compresses even further by upx before creating the
> image so that the image size get reduced further.

 I guess you could write a post-build script that runs upx on all executable
files in ${TARGET_DIR}/bin and  ${TARGET_DIR}/usr/bin.

 To get good results, I expect you need to combine it with BR2_STATIC_LIBS.
Otherwise a large fraction of the total size will be in shared libraries instead
of executables, and I don't think those can be compressed. And then, you'd
probably also want to globally enable LTO - but Buildroot doesn't have good
support for that at this time.

 I expect that the net benefit will be limited though. You're going to be better
off with a rootfs that is compressed at the filesystem level, e.g. squashfs or
ubifs.

 Regards,
 Arnout