From: Paolo Bonzini <pbonzini@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: mttcg@greensocs.com, "QEMU Developers" <qemu-devel@nongnu.org>,
"KONRAD Frédéric" <fred.konrad@greensocs.com>
Subject: Re: [Qemu-devel] [PATCH 05/10] cpu-exec: elide more icount code if CONFIG_USER_ONLY
Date: Sat, 29 Aug 2015 09:07:58 +0200 [thread overview]
Message-ID: <55E15A4E.6080009@redhat.com> (raw)
In-Reply-To: <CAFEAcA8ob8A+Sa4ytM=xOadQ26ezr6EhzEy=cGkP9U32MSYBZg@mail.gmail.com>
On 28/08/2015 16:56, Peter Maydell wrote:
> What's the rationale for this? Mostly we prefer not to
> add ifdefs in code if we can get away with compiling it for
> both cases, even if the resulting code isn't used.
True. The rationale is three-fold:
1) It makes sense to abort if TB_EXIT_ICOUNT_EXPIRED is returned from
user-mode emulation TCG code. Then you need to either leave the
unreachable code after abort() or #ifdef cpu_exec_nocache out.
2) Dually, cpu_exec_nocache's future locking requirements (take tb_lock,
mostly) are not yet respected as of this patch. Marking the function as
#ifdef CONFIG_SOFTMMU explains why. Once you do that, you have to
abort() either in cpu_exec_nocache or in the caller.
Reason (2) is stronger for me. You mentioned a few times your hope that
MTTCG would lead to more correct and more documented thread support in
user-mode emulation, and I think this patch does improve the
documentation slightly.
Paolo
next prev parent reply other threads:[~2015-08-29 7:08 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-12 16:40 [Qemu-devel] [PATCH 00/10] translate-all.c thread-safety Paolo Bonzini
2015-08-12 16:40 ` [Qemu-devel] [PATCH 01/10] cpus: protect work list with work_mutex Paolo Bonzini
2015-08-28 14:33 ` Peter Maydell
2015-08-12 16:40 ` [Qemu-devel] [PATCH 02/10] cpus: remove tcg_halt_cond global variable Paolo Bonzini
2015-08-13 13:05 ` Frederic Konrad
2015-08-13 13:08 ` Paolo Bonzini
2015-08-13 13:19 ` Frederic Konrad
2015-08-28 14:36 ` Peter Maydell
2015-08-29 6:52 ` Paolo Bonzini
2015-08-12 16:40 ` [Qemu-devel] [PATCH 03/10] replace spinlock by QemuMutex Paolo Bonzini
2015-08-13 12:17 ` Frederic Konrad
2015-08-13 13:12 ` Paolo Bonzini
2015-08-13 13:21 ` Frederic Konrad
2015-08-28 14:49 ` Peter Maydell
2015-08-28 14:53 ` Frederic Konrad
2015-08-29 6:51 ` Paolo Bonzini
2015-08-12 16:40 ` [Qemu-devel] [PATCH 04/10] exec-all: remove non-TCG stuff from exec-all.h header Paolo Bonzini
2015-08-28 14:53 ` Peter Maydell
2015-08-29 6:55 ` Paolo Bonzini
2015-08-12 16:40 ` [Qemu-devel] [PATCH 05/10] cpu-exec: elide more icount code if CONFIG_USER_ONLY Paolo Bonzini
2015-08-13 13:14 ` Frederic Konrad
2015-08-13 14:06 ` Paolo Bonzini
2015-08-28 14:56 ` Peter Maydell
2015-08-29 7:07 ` Paolo Bonzini [this message]
2015-08-12 16:40 ` [Qemu-devel] [PATCH 06/10] tcg: code_bitmap is not used by user-mode emulation Paolo Bonzini
2015-08-28 14:57 ` Peter Maydell
2015-08-29 7:13 ` Paolo Bonzini
2015-08-12 16:40 ` [Qemu-devel] [PATCH 07/10] tcg: comment on which functions have to be called with mmap_lock held Paolo Bonzini
2015-08-28 15:33 ` Peter Maydell
2015-08-29 6:57 ` Paolo Bonzini
2015-08-12 16:41 ` [Qemu-devel] [PATCH 08/10] tcg: add memory barriers in page_find_alloc accesses Paolo Bonzini
2015-08-12 20:37 ` Emilio G. Cota
2015-08-13 8:13 ` Paolo Bonzini
2015-08-13 19:50 ` Emilio G. Cota
2015-08-28 15:40 ` Peter Maydell
2015-08-29 6:58 ` Paolo Bonzini
2015-08-12 16:41 ` [Qemu-devel] [PATCH 09/10] exec: make mmap_lock/mmap_unlock globally available Paolo Bonzini
2015-08-28 15:42 ` Peter Maydell
2015-08-12 16:41 ` [Qemu-devel] [PATCH 10/10] cpu-exec: fix lock hierarchy for user-mode emulation Paolo Bonzini
2015-08-28 15:59 ` Peter Maydell
2015-08-12 16:41 ` [Qemu-devel] [PATCH 11/10] tcg: comment on which functions have to be called with tb_lock held Paolo Bonzini
2015-08-13 12:51 ` Frederic Konrad
2015-08-13 12:59 ` Paolo Bonzini
2015-08-13 13:32 ` Frederic Konrad
2015-08-13 14:39 ` Paolo Bonzini
2015-08-13 15:32 ` Peter Maydell
2015-08-13 16:20 ` Paolo Bonzini
2015-08-12 16:41 ` [Qemu-devel] [PATCH 12/10] tcg: protect TBContext with tb_lock Paolo Bonzini
2015-08-13 12:57 ` Frederic Konrad
2015-08-13 13:01 ` Paolo Bonzini
2015-08-13 13:04 ` Frederic Konrad
2015-08-14 9:26 ` [Qemu-devel] [PATCH 00/10] translate-all.c thread-safety Frederic Konrad
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=55E15A4E.6080009@redhat.com \
--to=pbonzini@redhat.com \
--cc=fred.konrad@greensocs.com \
--cc=mttcg@greensocs.com \
--cc=peter.maydell@linaro.org \
--cc=qemu-devel@nongnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.