How is your container filesystem setup/configured? It looks like the filesystem
isn't liking the build trying to create hardlinked files. It is odd it would
get as far as gmp-native before having problems. That file definitely isn't a
directory too, it is an odd error.
Thanks Richard, I suspect you're right. I'm using fuse-overlayfs which I'm mounting with the 'noxattrs' option because the host is Fedora and its SELinux configuration interferes with yocto in other ways. It looks like overlayfs uses xattrs in some cases for hard link resolution. I'll have to dig in deeper there, thanks for the pointer.
Cheers,
Simon.