All of lore.kernel.org
 help / color / mirror / Atom feed
From: "Alex Bennée" <alex.bennee@linaro.org>
To: Dino Papararo <skizzato73@msn.com>
Cc: qemu-devel@nongnu.org, Programmingkid <programmingkidx@gmail.com>,
	"qemu-ppc@nongnu.org" <qemu-ppc@nongnu.org>,
	Howard Spoelstra <hsp.cat7@gmail.com>,
	luigi burdo <intermediadc@hotmail.com>,
	David Gibson <david@gibson.dropbear.id.au>
Subject: Re: R: [RFC PATCH v2] target/ppc: Enable hardfloat for PPC
Date: Wed, 26 Feb 2020 14:28:45 +0000	[thread overview]
Message-ID: <87eeuhxw0y.fsf@linaro.org> (raw)
In-Reply-To: <AM4PR07MB350651FBB263FEEDB857CBFFCAEA0@AM4PR07MB3506.eurprd07.prod.outlook.com>


Dino Papararo <skizzato73@msn.com> writes:

> Please let's go with hardfloat pps support, it's really a good feature to implement.
> Even if in a first step it could lead to inaccuracy results, later it
> could solved with other patches.

That's the wrong way around. We have regression tests for a reason. I'll
happily accept patches to turn on hardfloat for PPC if:

 a) they don't cause regressions in our fairly extensive floating point
 tests
 b) the PPC maintainers are happy with the new performance profile

The way forward would be to:

 1. patch to drop #if defined(TARGET_PPC) || defined(__FAST_MATH__)
 2. audit target/ppc/fpu_helper.c w.r.t chip manual and fix any unneeded
 splatting of flags (if any)
 3. measure the before/after performance effect and decide if on balance
 it's worth keeping

> I think it's important for qemu to as global as possible and don't
> target only recent hardware.

Are you referring to guests or hosts? For guests we will always favour
accuracy of speed of emulation. For hosts we need to have IEEE compliant
FPU HW to even stand a chance of using hardfloat.

-- 
Alex Bennée


  reply	other threads:[~2020-02-26 14:29 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-18 17:10 [RFC PATCH v2] target/ppc: Enable hardfloat for PPC BALATON Zoltan
2020-02-18 17:38 ` BALATON Zoltan
2020-02-19  2:27 ` Programmingkid
2020-02-19 15:35   ` BALATON Zoltan
2020-02-19 18:28     ` Howard Spoelstra
2020-02-19 19:28       ` BALATON Zoltan
2020-02-20  5:43         ` Howard Spoelstra
2020-02-25  3:07     ` Programmingkid
2020-02-25 12:09       ` BALATON Zoltan
2020-02-26 10:46         ` Programmingkid
2020-02-26 11:28           ` BALATON Zoltan
2020-02-26 13:00             ` R: " luigi burdo
2020-02-26 13:08               ` Dino Papararo
2020-02-26 14:28                 ` Alex Bennée [this message]
2020-02-26 15:50                   ` Aleksandar Markovic
2020-02-26 17:04                     ` G 3
2020-02-26 17:27                       ` Aleksandar Markovic
2020-02-26 18:14                         ` R: " Dino Papararo
2020-02-26 18:51                           ` Aleksandar Markovic
2020-02-27  2:43                         ` Programmingkid
2020-02-27  7:16                           ` Aleksandar Markovic
2020-02-27 11:54                             ` BALATON Zoltan
2020-02-26 18:09                       ` R: " Alex Bennée
2020-03-02  0:13                         ` Programmingkid
2020-03-02  4:28                           ` Richard Henderson
2020-03-02 11:42                             ` BALATON Zoltan
2020-03-02 16:55                               ` Richard Henderson
2020-03-02 23:16                                 ` BALATON Zoltan
2020-03-03  0:11                                   ` Richard Henderson
     [not found]                                   ` <CAKyx-3Pt2qLPXWQjBwrHn-nxR-9e++TioGp4cKFC3adMN3rtiw@mail.gmail.com>
2020-03-04 18:43                                     ` Fwd: " G 3
2020-03-05 19:25                                       ` Richard Henderson
2020-03-02 17:10                               ` Alex Bennée
2020-03-02 23:01                                 ` BALATON Zoltan
2020-02-26 22:51                   ` R: " BALATON Zoltan
2020-02-20 20:13 ` Richard Henderson
2020-02-21 16:04   ` BALATON Zoltan
2020-02-21 16:11     ` Peter Maydell
2020-02-21 16:51       ` Aleksandar Markovic
2020-02-21 18:04       ` BALATON Zoltan
2020-02-21 18:26         ` Peter Maydell
2020-02-21 19:52           ` BALATON Zoltan
2020-02-26 12:28             ` Alex Bennée
2020-02-26 13:07               ` BALATON Zoltan
2020-04-10 13:50 ` 罗勇刚(Yonggang Luo)
2020-04-10 18:04   ` BALATON Zoltan

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=87eeuhxw0y.fsf@linaro.org \
    --to=alex.bennee@linaro.org \
    --cc=david@gibson.dropbear.id.au \
    --cc=hsp.cat7@gmail.com \
    --cc=intermediadc@hotmail.com \
    --cc=programmingkidx@gmail.com \
    --cc=qemu-devel@nongnu.org \
    --cc=qemu-ppc@nongnu.org \
    --cc=skizzato73@msn.com \
    /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.