On Fri, 23 Dec 2022 at 08:50, Alexander Graf <ag...@csgraf.de> wrote: > > While trying to make Windows work with GICv3 emulation, I stumbled over > the fact that it only supports ITT entry sizes that are power of 2 sized. > > While the spec allows arbitrary sizes, in practice hardware will always > expose power of 2 sizes and so this limitation is not really a problem > in real world scenarios. However, we only expose a 12 byte ITT entry size > which makes Windows blue screen on boot. > > The easy way to get around that problem is to bump the size to 16. That > is a power of 2, basically is what hardware would expose given the amount > of bits we need per entry and doesn't break any existing scenarios. To > play it safe, this patch set only bumps them on newer machine types.
This is a Windows bug and should IMHO be fixed in that guest OS. Changing the ITT entry size of QEMU's implementation introduces an unnecessary incompatibility in migration and wastes memory (we're already a bit unnecessarily profligate with ITT entries compared to real hardware). thanks -- PMM
