Xen 4.14 build failing on aarch64 with GCC 10.2.1

[Roman Shaposhnik <roman@xxxxxxxxxx>]

Hi!

just came across this failure on aarch64:

ld: prelink.o: in function `_spin_lock_cb':
19187(.text+0x1f26c): undefined reference to `__aarch64_ldadd4_acq_rel'
19188ld: prelink.o: in function `_spin_lock':
19189(.text+0x1f2ec): undefined reference to `__aarch64_ldadd4_acq_rel'
19190ld: prelink.o: in function `_spin_lock_irq':
19191(.text+0x1f35c): undefined reference to `__aarch64_ldadd4_acq_rel'
19192ld: prelink.o: in function `_spin_lock_irqsave':
19193(.text+0x1f3d4): undefined reference to `__aarch64_ldadd4_acq_rel'
19194ld: prelink.o: in function `_spin_lock_recursive':
19195(.text+0x1f6b0): undefined reference to `__aarch64_ldadd4_acq_rel'

This, of course, goes away if I build Xen with:
   CFLAGS=-mno-outline-atomics

However, at this point I'm curious if this is going to get addressed in Xen
proper or not.

Thanks,
Roman.