From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9B2A3C77B6E for ; Wed, 12 Apr 2023 15:37:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229994AbjDLPhk (ORCPT ); Wed, 12 Apr 2023 11:37:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42308 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231574AbjDLPhg (ORCPT ); Wed, 12 Apr 2023 11:37:36 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BC7A283E3 for ; Wed, 12 Apr 2023 08:37:30 -0700 (PDT) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1681313848; 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=k3KOK2E2+YL0UWZuMxIugWW/8u560Xs4Osw19RDEBOc=; b=jJKraW6sibyV19gFvOdSg/5yJbD6XCrhTn/9AosBMVHK+hr1IUMi2d56CHi4QGDf5CEaEq PzmGZMGZjcdYcDZLQZDltUhPS+yZDUtP0MMT43bzcC5AX9sYO0+G4CeR5ZjxAzrYLEemyu F8VZTjrR5VPrqbErETPifdMPyKKNigvES7yMboQ1m501TOX60p7fE2ghdj5MmLDgqhsv9n glICORo8KtB71L5THRv+lNrZZPBFCX2ZVuxXfNGKrlXrZWbGK9A/MjHOcos8CIPbPtvaM1 HkTKlyJZ2h0xLC/lMGiFfG1tXsqaIpOerJYNwiSE0CwO2eXjLtFz8uxCWIijLA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1681313848; 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=k3KOK2E2+YL0UWZuMxIugWW/8u560Xs4Osw19RDEBOc=; b=EY8KgjIqD4lzsVy1JVTclcJnAREGgvIFTNOVYzfEz5HAU8G988gz5Wdo1w7gqZaxENeA63 darbyuPS1kMwFoBA== To: Saurabh Singh Sengar , "H. Peter Anvin" Cc: mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, johan+linaro@kernel.org, isaku.yamahata@intel.com, mikelley@microsoft.com, linux-kernel@vger.kernel.org, andriy.shevchenko@intel.com Subject: Re: [PATCH v2] x86/ioapic: Don't return 0 from arch_dynirq_lower_bound() In-Reply-To: <20230328144834.GA17868@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net> References: <1679988604-20308-1-git-send-email-ssengar@linux.microsoft.com> <3D028B51-35D7-435F-B912-DC5C0D6C36C6@zytor.com> <20230328144834.GA17868@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net> Date: Wed, 12 Apr 2023 17:37:27 +0200 Message-ID: <87v8i1yuvc.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 28 2023 at 07:48, Saurabh Singh Sengar wrote: > On Tue, Mar 28, 2023 at 06:59:04AM -0700, H. Peter Anvin wrote: >> >> Is there any reason why this variable can't be initialized to a fixed nonzero number, like 16? > > Yes, initializing gst_top to any non-zero value should fix this issue. > At first I thought to intialize gst_top to 1. That works only in your case. Some boot time registrations of IO_APICs use gsi_top as the base. So initializing gsi_top to N would move IOAPIC[0] interrupts out to irq N... and make the legacy interrupts fail. That whole IOAPIC registration could do with some major cleanup, but that's a different story. Thanks, tglx