On Thu, May 20, 2021 at 01:24:02PM +0200, Marek Behún wrote:
Currently we use incremental linking (ld -r) to link several object files from one directory into one built-in.o object file containing the linked code from that directory (and its subdirectories).
Linux has, some time ago, moved to thin archives instead.
Thin archives are archives (.a) that do not really contain the object files, only references to them.
Using thin archives instead of incremental linking
- saves disk space
- apparently works better with dead code elimination
- makes things easier for LTO
The third point is the important one for us. With incremental linking there are several options how to do LTO, and that would unnecessarily complicate things.
We have to use the --whole-archive/--no-whole-archive linking option instead of --start-group/--end-group, otherwise linking may fail because of unresolved symbols, or the resulting binary will be unusable.
We also need to use the P flag for ar, otherwise final linking may fail.
Signed-off-by: Marek Behún marek.behun@nic.cz Reviewed-by: Simon Glass sjg@chromium.org
Applied to u-boot/master, thanks!