On 11/4/21 6:25 PM, Daniel P. Berrangé wrote:
On Thu, Nov 04, 2021 at 01:22:53PM +0100, Michal Privoznik wrote:
Alright, here's the deal: to enable tb-cache one has to use '-accel tcg,tb-size=' which then conflicts with '-machine accel=tcg'. But sure, we can use the old -accel in this specific case. But because of how the tb-size argument is defined in QEMU there's no way for us to have a capability check. The feature was introduced in QEMU commit of v5.0.0-rc0~175^2~62 and is tied to TCG only. Therefore, I think we can live without capability check. Worst case scenario, QEMU fails to start.
Resolves: https://gitlab.com/libvirt/libvirt/-/issues/229 Signed-off-by: Michal Privoznik <mprivozn@redhat.com> --- src/qemu/qemu_command.c | 14 ++++++- ...efault-cpu-tcg-features.x86_64-latest.args | 40 +++++++++++++++++++ tests/qemuxml2argvtest.c | 1 + 3 files changed, 54 insertions(+), 1 deletion(-) create mode 100644 tests/qemuxml2argvdata/x86_64-default-cpu-tcg-features.x86_64-latest.args
IOW, long term we want to be using -accel exclusively.
Given our minimum QEMU 2.11.0, we can in fact use -accel exclusively already AFAICT.
That would simplify this patch so that we're not supporting distinct syntax with tb_cache.
Ah, I don't know why I thought the opposite. Let me post v2. Michal