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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-45edb558dd0sm4453194f8f.16.2026.05.27.02.09.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 May 2026 02:09:44 -0700 (PDT) Date: Wed, 27 May 2026 10:09:43 +0100 From: David Laight To: "H. Peter Anvin" Cc: "Maciej W. Rozycki" , Christian Ludloff , Dave Hansen , Richard Weinberger , Sohil Mehta , "Ahmed S. Darwish" , Borislav Petkov , x86@kernel.org, Thomas Gleixner , Ingo Molnar , Josh Poimboeuf , Andrew Cooper , Tony Luck , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/3] x86/cpu/intel: Simplify F00F bug notice using pr_notice_once() Message-ID: <20260527100943.37d67776@pumpkin> In-Reply-To: <48C91A0E-043C-4E24-99E5-DE64B9F47C3A@zytor.com> References: <20260526162041.5b7e6614@pumpkin> <48C91A0E-043C-4E24-99E5-DE64B9F47C3A@zytor.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 26 May 2026 13:49:08 -0700 "H. Peter Anvin" wrote: > On May 26, 2026 12:15:19 PM PDT, "Maciej W. Rozycki" 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