From: David Laight <david.laight.linux@gmail.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Maciej W. Rozycki" <macro@orcam.me.uk>,
Christian Ludloff <ludloff@gmail.com>,
Dave Hansen <dave.hansen@intel.com>,
Richard Weinberger <richard@nod.at>,
Sohil Mehta <sohil.mehta@intel.com>,
"Ahmed S. Darwish" <darwi@linutronix.de>,
Borislav Petkov <bp@alien8.de>,
x86@kernel.org, Thomas Gleixner <tglx@kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Tony Luck <tony.luck@intel.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/3] x86/cpu/intel: Simplify F00F bug notice using pr_notice_once()
Date: Wed, 27 May 2026 10:09:43 +0100 [thread overview]
Message-ID: <20260527100943.37d67776@pumpkin> (raw)
In-Reply-To: <48C91A0E-043C-4E24-99E5-DE64B9F47C3A@zytor.com>
On Tue, 26 May 2026 13:49:08 -0700
"H. Peter Anvin" <hpa@zytor.com> wrote:
> On May 26, 2026 12:15:19 PM PDT, "Maciej W. Rozycki" <macro@orcam.me.uk> wrote:
> >On Tue, 26 May 2026, Christian Ludloff wrote:
> >
> >> > > > This actually continues getting serious use, most recently for glibc ISO
> >> > > > C formatted input/output test coverage improvement and the x87 FP formats.
> >>
> >> x87 testing... on a Pentium?
> >
> > Yes, 32-bit x86 remains a supported target with the GNU C library, down
> >to i486 I believe, that includes dedicated platform code such as for the
> >80-bit extended format, so this was a good portability exercise, given
> >that the scope of the tests were floating-point formatted input/output
> >specifiers, not previously sufficiently covered.
> >
> > Maciej
>
> However, x87 should be testable on any x86 silicon.
And gets used for 'long double' on x86-64.
If full precision is enabled there are a whole lot of horrid corner cases.
Mostly due to correctly generating the FP signals when the 80bit return
value from a function is written to a 64bit 'double'.
-- David
next prev parent reply other threads:[~2026-05-27 9:09 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-15 0:24 [PATCH v2 0/3] x86: Fix a F00F bug warning and cleanup surrounding code Sohil Mehta
2026-05-15 0:24 ` [PATCH v2 1/3] x86/cpu/intel: Don't clear X86_BUG_F00F before setting it Sohil Mehta
2026-05-15 19:16 ` Ahmed S. Darwish
2026-05-15 0:24 ` [PATCH v2 2/3] x86/cpu/intel: Simplify F00F bug notice using pr_notice_once() Sohil Mehta
2026-05-15 19:14 ` Ahmed S. Darwish
2026-05-15 22:37 ` Sohil Mehta
2026-05-15 23:09 ` Ahmed S. Darwish
2026-05-15 23:23 ` Dave Hansen
2026-05-18 20:29 ` Sohil Mehta
2026-05-18 21:17 ` Dave Hansen
2026-05-18 21:23 ` H. Peter Anvin
2026-05-21 22:38 ` Maciej W. Rozycki
2026-05-22 6:11 ` Christian Ludloff
2026-05-22 20:27 ` Maciej W. Rozycki
2026-05-25 10:41 ` Maciej W. Rozycki
2026-05-26 20:56 ` Richard Weinberger
2026-05-27 0:25 ` Maciej W. Rozycki
2026-05-26 14:14 ` Dave Hansen
2026-05-26 15:01 ` Maciej W. Rozycki
2026-05-26 15:20 ` David Laight
2026-05-26 17:43 ` Christian Ludloff
2026-05-26 19:15 ` Maciej W. Rozycki
2026-05-26 20:49 ` H. Peter Anvin
2026-05-27 0:29 ` Maciej W. Rozycki
2026-05-27 6:13 ` H. Peter Anvin
2026-05-27 9:09 ` David Laight [this message]
2026-05-27 9:23 ` Maciej W. Rozycki
2026-05-27 15:36 ` H. Peter Anvin
2026-05-27 16:14 ` Maciej W. Rozycki
2026-06-01 14:43 ` H. Peter Anvin
2026-06-01 21:45 ` David Laight
2026-05-15 0:25 ` [PATCH v2 3/3] x86/cpufeature: Remove clear_cpu_bug() Sohil Mehta
2026-05-15 19:16 ` Ahmed S. Darwish
2026-05-15 6:18 ` [PATCH v2 0/3] x86: Fix a F00F bug warning and cleanup surrounding code Richard Weinberger
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