On 29/04/2020 18:17, Ayush Dosaj wrote: > Hi Xen development team, > > I am Ayush. I compiled Xen Hypervisor from source on Ubuntu 20.04 > machine running on an intel-i9 CPU. > I am getting compilation error due to the following two flags. > Error: error: ‘-mindirect-branch’ and ‘-fcf-protection’ are not compatible. > > Complete Error logs can be found at https://paste.ubuntu.com/p/xvvyPnhW5c/ > > And when I compiled Xen commenting the two flags in Rules.mk file, it > compiles and installs properly but on boot-up i see a blank black screen > and i am stuck there.
That is a GCC bug (these options are actually fine in combination). It got fixed earlier today in master, and backported for GCC 9.4 You can work around it by appending -fcf-protection=none to CFLAGS I wouldn't try editing the logic around -mindirect-branch, as that is related to retpoline safety for Spectre v2, and probably relies on the build matching the code. ~Andrew
