Re: [PATCH 2/2] qemu: Generate command line for tb-cache feature

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(a)redhat.com&gt; >> --- >> 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.