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Re: [Qemu-devel] [PATCH v7 05/27] tcg: add options for enabling MTTCG
From: |
Alex Bennée |
Subject: |
Re: [Qemu-devel] [PATCH v7 05/27] tcg: add options for enabling MTTCG |
Date: |
Tue, 24 Jan 2017 20:25:59 +0000 |
User-agent: |
mu4e 0.9.19; emacs 25.1.91.4 |
Richard Henderson <address@hidden> writes:
> On 01/19/2017 09:04 AM, Alex Bennée wrote:
>> +void qemu_tcg_configure(QemuOpts *opts, Error **errp)
>> +{
>> + const char *t = qemu_opt_get(opts, "thread");
>> + if (t) {
>> + if (strcmp(t, "multi") == 0) {
>> + if (TCG_OVERSIZED_GUEST) {
>> + error_setg(errp, "No MTTCG when guest word size > hosts");
>
> I agree with this, since I don't ever imagine it'll be fixed. It's a silly
> use
> case in the first place considering the ubiquity of 64-bit hosts.
Funnily enough I know one kernel hacker who does use this to test their
arm64 kernels on their re-purposed armhf chromebooks. I've already
explained coming their way ;-)
>
>> + } else if (!check_tcg_memory_orders_compatible()) {
>> + error_setg(errp,
>> + "No MTTCG when guest MO is stronger than host
>> MO");
>
> This, on the other hand, means that one cannot even force multi for testing.
> A
> warning perhaps?
I did toy with making that a warning when I first wrote it. I'll make it so.
> And how shall we handle a guest translate adding barriers as
> necessary to satisfy host memory ordering?
We are talking about doing the necessary annotation to all a givens
targets loads and stores? I figured this code would morph and be tweaked
when (if?) we get there.
--
Alex Bennée
- [Qemu-devel] [PATCH v7 01/27] docs: new design document multi-thread-tcg.txt, (continued)
- [Qemu-devel] [PATCH v7 01/27] docs: new design document multi-thread-tcg.txt, Alex Bennée, 2017/01/19
- [Qemu-devel] [PATCH v7 06/27] tcg: add kick timer for single-threaded vCPU emulation, Alex Bennée, 2017/01/19
- [Qemu-devel] [PATCH v7 04/27] tcg: move TCG_MO/BAR types into own file, Alex Bennée, 2017/01/19
- [Qemu-devel] [PATCH v7 07/27] tcg: rename tcg_current_cpu to tcg_current_rr_cpu, Alex Bennée, 2017/01/19
- [Qemu-devel] [PATCH v7 05/27] tcg: add options for enabling MTTCG, Alex Bennée, 2017/01/19
- Re: [Qemu-devel] [PATCH v7 05/27] tcg: add options for enabling MTTCG, Richard Henderson, 2017/01/23
[Qemu-devel] [PATCH v7 09/27] tcg: remove global exit_request, Alex Bennée, 2017/01/19
[Qemu-devel] [PATCH v7 02/27] mttcg: translate-all: Enable locking debug in a debug build, Alex Bennée, 2017/01/19
[Qemu-devel] [PATCH v7 10/27] tcg: enable tb_lock() for SoftMMU, Alex Bennée, 2017/01/19
[Qemu-devel] [PATCH v7 08/27] tcg: drop global lock during TCG code execution, Alex Bennée, 2017/01/19
[Qemu-devel] [PATCH v7 12/27] tcg: handle EXCP_ATOMIC exception for system emulation, Alex Bennée, 2017/01/19
[Qemu-devel] [PATCH v7 11/27] tcg: enable thread-per-vCPU, Alex Bennée, 2017/01/19
[Qemu-devel] [PATCH v7 13/27] cputlb: add assert_cpu_is_self checks, Alex Bennée, 2017/01/19
[Qemu-devel] [PATCH v7 14/27] cputlb: tweak qemu_ram_addr_from_host_nofail reporting, Alex Bennée, 2017/01/19