From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 950CE3EBF3C for ; Thu, 12 Feb 2026 15:18:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770909521; cv=none; b=SoVeLthOZibSTVQso057PXFGX+AeyqGNXyRPzOwSpZeDq+ahCqJG+CAnKR0gCty5DVHA0pKUPDAqNx/8MWp2UxvkvSmTNAXnAPdL0G9LQ59BRCTVgKwRB1UkFxmtHzqSTqgGtkNU1N1YSv93vsJH+C8vKtgwM13u34k8Ls/h0v8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770909521; c=relaxed/simple; bh=ai5+4phpGGg9Zf2/MzswoaaLkZJhMjczH6MtkTFYiDo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=b0v/RbhfVb8UfWvz7kJpDxV7S+2X7/rztNCwEWoV3s5wD1CdXgGnnieKVVeUiIzqm1Gi53FUyziwskM+eFgSwqQTo4wydzPjMnfLrGl00Cf803n1gMY0hE6fdWhQqkwTXKJdQC2dwspIgfGtVQWnxfLvqp3H41fHsRGuqiSENpg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=NXAXFZMz; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=6iTTKLuH; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="NXAXFZMz"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="6iTTKLuH" Date: Thu, 12 Feb 2026 16:18:35 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1770909516; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=SGzf6YJRP8H9TbMz2kFAMAC0ww4swNjoJ2X6kO51pI4=; b=NXAXFZMzFKsu3TQWxkx/BzaMjJ5wh1BhqgUFgpk5LnoCEDxGwPYreHmOifj6nINpSZPnXf XbTXy3A2tPNcS0/OqjTijJTyyThlGcRljq9AGipKIJciI03nJ65Ha3iUzEGLctrRGkhgvA PcsvuyIUgv1FAOcT3CuzzxvB20IMDDNPfsXKvPlOr/5W4PovrWWcqzKhuLu/ackf4moOdA uJCG6TH0rNhiYZQRKn13WnC9Pfiogvd9kxktkL9a7lNuC1Z5sWb2bI+MbmI2jL/vf+XUI1 opowre9I1KhWyUzUzZGYDq1COdGSIrOY8mbKBoU1UFxZzPt+nbK8Gw1mqohjwg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1770909516; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=SGzf6YJRP8H9TbMz2kFAMAC0ww4swNjoJ2X6kO51pI4=; b=6iTTKLuHeo8tsKSEw2Tb3IhQl9uQNa4hmagPRfUl9Bj0V11NbFx4BiHkNOf5G0F3mJpVJc qVqGeEDXXcQBZpAQ== From: Sebastian Andrzej Siewior To: Ard Biesheuvel Cc: linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, "Luis Claudio R. Goncalves" , John Ogness , Lai Jiangshan , Tejun Heo Subject: Re: [PATCH 0/2] efi: Expose the runtime-services workqueue via sysfs Message-ID: <20260212151835.8On7hOkI@linutronix.de> References: <20260205115559.1625236-1-bigeasy@linutronix.de> <4c6a5533-6fcd-4237-bb35-0ca74029c7db@app.fastmail.com> Precedence: bulk X-Mailing-List: linux-rt-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <4c6a5533-6fcd-4237-bb35-0ca74029c7db@app.fastmail.com> On 2026-02-09 18:10:52 [+0100], Ard Biesheuvel wrote: > Hello Sebastian, > > On Thu, 5 Feb 2026, at 12:55, Sebastian Andrzej Siewior wrote: > > EFI runtime services are disabled on PREEMPT_RT by default which can be > > overwritten on the boot command line. For native EFI, an invocation > > requires to disable preemption while a call is made into EFI. > > This is no longer true on arm64 since > > commit a5baf582f4c026c25a206ac121bceade926aec74 > Author: Ard Biesheuvel > Date: Wed Oct 15 22:56:42 2025 +0200 > > arm64/efi: Call EFI runtime services without disabling preemption > > except for some corner cases (reboot, pstore crash dump). Hmm. While this sounds familiar (and I think you told me that FPU usage no longer disables preemption here, too) there is x86 for instance. Here arch_efi_call_virt_setup() disables preemption twice (efi_fpu_begin() + (firmware_restrict_branch_speculation_start()) followed by efi_call_virt_save_flags() where interrupts are off. Also I don't know if the EFI implementation itself is allowed to disable interrupts. > > There are two EFI invocations which are not covered by this > > - mixed EFI > > Used on x86 with 64bit kernel but 32bit EFI. Would it work to use here > > the same workqueue mechanism? > > > > That stuff is beyond obsolete, so I don't think it is relevant for RT. agreed. > Acked-by: Ard Biesheuvel Oh. Thank you. Sebastian