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[81.2.115.145]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43d63e46713sm32893051f8f.21.2026.04.13.03.37.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Apr 2026 03:37:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1776076675; x=1776681475; darn=nongnu.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=/gRv9RLfF/F+lj385yyoTJLt207V/mbUmBgkzmiVuuw=; b=LNt2gAR/dlr21TUCevbumLhYgrg4sk+C2jLRYKumROvX1b40Asz/XVUNYg8Enk480x HRzhCg9cIejpdgxwslkGPSwHGIj9Ou/XQE4JYIeed4TQv1wiHZCNzuwjBoNCmYNqqO8j Aa//y5DE4eAhhIqruOO7oc13whBUaX61Uqe2FjBUo45Qlewg2JQVRb+b4c4rUEO9xjmu NkIMPuidp8sBzgtqBGZyF5aII1EBIaYcbwtb0et/krHakhzOiDzBQuNRBAEKIZpe/pHk 0p+w1LU0mfRcwxMSlctJS/XQ32L0pi8ucH28H5Oqc6bTP+gCiMkl7rxpDYSoE7wopGyR 1AeA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776076675; x=1776681475; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=/gRv9RLfF/F+lj385yyoTJLt207V/mbUmBgkzmiVuuw=; b=K3p1b7yCx7+ijEhRtsTXBim2WNCJ9/3v+Xs6aDDYVMKL9JPpKLHDiTQLNbEKkrIyh4 rLsX3mq1ekOnHc3O4xvbd96ngdLW7P6JjLAPis3qrsHqp5x/bi1uMP4CW5VcxT1ZXxWQ OdDgaKJYsuqqh+AXPyemBdzVnCA26LgrQrl6L2KMHLrMdp+TqWug93kZ6R/rldilngfC F93VGLQQ+7Waqc4BaO4XOqqKek+L9DZN9Rgsqh/uzTVlzXwZjbOzQTx4Kv3gTEgX3FH8 B+0YDrqrEMc0WhOuAd1HR5TDcx3bV9Rmz3BVfeY9IWtpVwVADJ+YIM5sHglIsP1B28aC ZIIg== X-Forwarded-Encrypted: i=1; AFNElJ/QjiubEg2bYrnCCAWZFvmFAgZ7Zhv8TU3v9sGvGSY7yn5smXRWZXMfhdqP2CSdBRFBWjK98eyD9zCd@nongnu.org X-Gm-Message-State: AOJu0YzP4rMVdIWjnN4axVCbWXwzjhuigZ0Jcqs1dyx4CaUiJgpRnLg9 lYug+xViC2gJvKsiHmhdDRa9m4Olwcrr7TqiHEu6yEx33MlwmT5frCDwzbWaLvUPWyI= X-Gm-Gg: AeBDieua70ZcBiq7MPpcxfJMQrnJsOyTA1XHWf5t/8sKXUzMyNG/kquu4BTNK0oIASa LgKD+f9LbeQmIHJtpYcrne4CGLtTo5t01FjC3bucgjokqvZNaa5AbybyX/vwLbJo9OiHt19owDS 24n85mQZpG90GpXXAS+kkRhjuq/H6NVOLSIivKDGdAyw0DKTnjcFzuMi6B29yodUmcAZBV1hAZl H8TCc9YMSOB0LfIC6Y69F828DhGkjKgrGn8R3g2HVLXsWCYy83FuBSJNAlRPmVirUr9ssaJQoMh oqigjYVlThsNAmx9qVQX8R+UOVMYN3jTwOKYTca8I+hgXvt24WpK4MnlkwKzL6kH3ll/6JigLsa bzLYu9NUE8fP9n9tfbQYM9CLMSJ/waSjorb46rIUMXq7adcSRtMMuhr/1j7l5jOv50O8NfT1aLP QAh1gBybh0yhjzjwZGWt/pq8uwGC3fklFTp3SHoFEsQeP7umbxn6yGy1xTC0KJy8UEpRpgX5QIB rfpKKC0J9ywe9uivbKfl/1sVyub7XIK7x1VX17r2Q== X-Received: by 2002:a05:600c:440f:b0:488:84b1:b216 with SMTP id 5b1f17b1804b1-488cd58011dmr160933685e9.9.1776076675363; Mon, 13 Apr 2026 03:37:55 -0700 (PDT) From: Peter Maydell To: qemu-arm@nongnu.org, qemu-devel@nongnu.org Cc: Richard Henderson Subject: [PATCH for-11.0 ?] docs: Deprecate Arm OABI and NWFPE support Date: Mon, 13 Apr 2026 11:37:54 +0100 Message-ID: <20260413103754.45745-1-peter.maydell@linaro.org> X-Mailer: git-send-email 2.43.0 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists1p.gnu.org; Received-SPF: pass client-ip=2a00:1450:4864:20::334; envelope-from=peter.maydell@linaro.org; helo=mail-wm1-x334.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @linaro.org) X-ZM-MESSAGEID: 1776076699076154100 Content-Type: text/plain; charset="utf-8" Linux for 32-bit Arm has had two major ABIs: the original OABI and the more modern EABI. OABI support was marked as obsolete in GCC 4.7 and dropped in GCC 4.8. In the Linux kernel, compatibility handling for OABI (OABI_COMPAT) is not generally enabled by default and is not compatible with building a Thumb2 kernel. Distros dropped OABI support fifteen years or more ago. NWFPE floating-point emulation handles the ancient FPA11 coprocessor, which is only needed/supported with OABI. Our implementation is old, untested and not thread-safe. Mark OABI and NWFPE support as deprecated so we can remove it in a future release. Our main motivation here is to be able to drop the 2500+ lines of NWFPE emulation code. Signed-off-by: Peter Maydell Reviewed-by: Alex Benn=C3=A9e Reviewed-by: Mohamed Mediouni Reviewed-by: Richard Henderson --- This just came up today; it's tempting to squeeze the deprecation notice into 11.0 so we don't have an extra three months before we can delete it, but we could just deprecate in 11.1 instead. docs/about/deprecated.rst | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst index a6d6a71326..10de10dc23 100644 --- a/docs/about/deprecated.rst +++ b/docs/about/deprecated.rst @@ -452,6 +452,31 @@ It was implemented as a no-op instruction in TCG up to= QEMU 9.0, but only with ``-cpu max`` (which does not guarantee migration compatibility across versions). =20 +linux-user mode CPUs +-------------------- + +OABI and NWFPE support for Arm CPUs +''''''''''''''''''''''''''''''''''' + +Linux for 32-bit Arm has had two major ABIs: the original OABI and the +more modern EABI. OABI support was marked as obsolete in GCC 4.7 and +dropped in GCC 4.8 (released in 2013). In the Linux kernel, +compatibility handling for OABI (OABI_COMPAT) is not generally enabled +by default and is not compatible with building a Thumb2 +kernel. Distros dropped OABI support fifteen years or more ago. + +The original floating-point coprocessor for 32-bit Arm was the +FPA11. This was not present in many CPUs but did get baked into the +OABI for how to pass floating point arguments, and so the Linux kernel +has support for emulating it via the config option FPE_NWFPE; QEMU +follows that. FPA11 support was also removed from GCC in GCC 4.8. + +QEMU's NWFPE code is old and untested and not thread-safe; the OABI +ABI is long-obsolete. We are therefore deprecating both OABI support +and NWFPE emulation, and they will be removed in a future QEMU +release. + + Backwards compatibility ----------------------- =20 --=20 2.43.0