From: mzoran@crowfest•net (Michael Zoran)
To: linux-arm-kernel@lists•infradead.org
Subject: ARM64: Disabling warnings about deprecated armv8 instructions
Date: Mon, 30 Jan 2017 10:34:59 -0800 [thread overview]
Message-ID: <1485801299.1085.0.camel@crowfest.net> (raw)
In-Reply-To: <yw1xo9yofm41.fsf@unicorn.mansr.com>
On Mon, 2017-01-30 at 18:17 +0000, M?ns Rullg?rd wrote:
> Michael Zoran <mzoran@crowfest•net> writes:
>
> > On Mon, 2017-01-30 at 17:09 +0000, Ard Biesheuvel wrote:
> > > Well, the question is really how to deal with 32-bit
> > > compatibility
> > > given the fact that the ARM architecture will drop such
> > > instructions
> > > in its next revision. Whether we agree with that, and whether we
> > > should argue our positions with the architects if we don't is not
> > > relevant here.
> > >
> > > What is relevant is whether we inform userspace if we spot such a
> > > deprecated instruction, and I think we should.
> > >
> > > Note that this is not only an issue for the arm64 kernel. The 32-
> > > bit
> > > kernel will have the exact same issue when you try to run it on
> > > hardware that no longer has support for those instructions.
> >
> > Just to inject two cents worth since I'm still on the thread and I
> > originally started the topic...
> >
> > The Intel comparison seems relevant.? I think in theory you can
> > still
> > run old MS-DOS software on an Intel PC if you were so inclined to
> > do
> > so.
> >
> > I would think the best would be to turn the warnings off by default
> > when running in 32 bit mode with the option to turn them back on.?
> > Then
> > as time progresses more of more of these instructions can be
> > converted
> > to software emulation and removed from the hardware.? And hopefully
> > as
> > time progresses, all the user mode software gets upgraded to 64 bit
> > so
> > that 32 bit get dropped.
> >
> > The issue seems to me to be more that the kernel is screaming in
> > the
> > logs rather then if it's emulating the instructions in hardware or
> > software.
>
> Might warning once be an acceptable compromise?
Absolutely!
next prev parent reply other threads:[~2017-01-30 18:34 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-22 8:07 ARM64: Disabling warnings about deprecated armv8 instructions Michael Zoran
2017-01-22 8:52 ` Alexander Stein
2017-01-22 8:58 ` Michael Zoran
2017-01-22 9:05 ` Jisheng Zhang
2017-01-22 9:38 ` Michael Zoran
2017-01-22 9:43 ` Ard Biesheuvel
2017-01-22 9:52 ` Michael Zoran
2017-01-22 9:56 ` Michael Zoran
2017-01-22 10:54 ` Ard Biesheuvel
2017-01-22 11:05 ` Michael Zoran
2017-01-22 11:22 ` Michael Zoran
2017-01-22 9:09 ` Ard Biesheuvel
2017-01-22 9:33 ` Michael Zoran
2017-01-22 9:36 ` Ard Biesheuvel
2017-01-22 9:49 ` Michael Zoran
2017-01-22 11:46 ` Alexander Stein
2017-01-22 12:21 ` Michael Zoran
2017-01-22 13:01 ` Ard Biesheuvel
2017-01-22 14:02 ` Michael Zoran
2017-01-22 15:05 ` Ard Biesheuvel
2017-01-30 14:13 ` Russell King - ARM Linux
2017-01-30 14:50 ` Ard Biesheuvel
2017-01-30 16:38 ` Måns Rullgård
2017-01-30 16:58 ` Russell King - ARM Linux
2017-01-30 17:09 ` Ard Biesheuvel
2017-01-30 17:39 ` Eric Anholt
2017-01-30 17:41 ` Michael Zoran
2017-01-30 18:17 ` Måns Rullgård
2017-01-30 18:34 ` Michael Zoran [this message]
2017-01-30 18:49 ` Will Deacon
2017-01-30 19:53 ` Michael Zoran
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=1485801299.1085.0.camel@crowfest.net \
--to=mzoran@crowfest$(echo .)net \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox