From: Alan Modra <amodra@gmail.com>
To: Peter Bergner <bergner@linux.ibm.com>
Cc: Waldemar Brodkorb <wbx@openadk.org>, binutils@sourceware.org
Subject: Re: regression with binutils 2.28 for ppc
Date: Sun, 20 Feb 2022 22:28:06 +1030 [thread overview]
Message-ID: <YhIszs/2D9l2VFvp@squeak.grove.modra.org> (raw)
In-Reply-To: <1f433717-0b26-4c53-6f21-9efeab7dcdc7@linux.ibm.com>
On Thu, Feb 17, 2022 at 10:21:30PM -0600, Peter Bergner wrote:
> On 2/17/22 7:34 PM, Alan Modra wrote:
> > On Thu, Feb 17, 2022 at 02:03:24PM -0600, Peter Bergner wrote:
> >> The use of those ptesyncs in the kernel really needs to be audited though!
> >> If they are legitimate, then the inline assembler needs to wrap their
> >> use with ".machine push ; .machine ppc64 ; ptesync ; .machine pop".
> >
> > Right. Or we should allow the user command line to control the
> > assembler, even with -Wa,-many if they so desire. But that's killed
> > by that stupid .machine from gcc.
>
> I thought we were moving towards more reliance on .machine and not away
> from it? You think we shouldn't be?
I thought it wasn't a great idea when we started using it in 2015 or
so. You can probably find archived email of me saying that. ;-)
Nothing has changed since then to make me think that gcc controlling
the assembler by both command-line options and a source directive at
the start of assembly is a good idea.
I'm tempted to hack gas to ignore the first .machine from gcc, if no
code has been emitted and the .machine is a subset of what is given by
the command line.
> This is probably the difference between new gccs emiting .machine ppc64
> when using -mcpu=powerpc64 and old gccs that emit .machine ppc.
Ah, gcc pr101393 (which was about 403, but same thing, .machine ppc
rather than the correct machine).
> Given all the above though, I'm surprised the kernel team hasn't hit
> this already and complained to us about it! :-)
I guess the focus has been on 64-bit kernels.
--
Alan Modra
Australia Development Lab, IBM
next prev parent reply other threads:[~2022-02-20 11:58 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-16 13:35 Waldemar Brodkorb
2022-02-16 14:32 ` Peter Bergner
2022-02-16 18:24 ` Peter Bergner
2022-02-17 9:28 ` Waldemar Brodkorb
2022-02-17 20:03 ` Peter Bergner
2022-02-18 1:34 ` Alan Modra
2022-02-18 4:21 ` Peter Bergner
2022-02-20 11:58 ` Alan Modra [this message]
2022-02-23 8:51 ` Alan Modra
2022-02-23 17:34 ` Waldemar Brodkorb
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