From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=193.175.24.41 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792835475; b=isG8Tko/7u6hCjTWbM4QOZNTJrcuU0Op7vxQlvh+c5UPl73kE6iceImXlgF21cRb0yx4 h4/KECo1QKDJl5z9GvVQcfe6xITgVyjLVNLx454diMsKkmqckbh+rwZl/gS1nByupj+EZ SkffqXwjXbltdIqwO/bf/MbWjC0FdEGpNN0GIkC7wOCeUnaFyWUfb91l3ZlmYH2dxUVhS YKgUHzO28o+WhYazvmczJ9ehlfqobtxvJXf0ILW1oKErRDETaEW3zFIKwMAe5U1nY1XAT tDUeTxGqSCavHiyaOL7hzgqt9ikgYS23SmezGTFmz7yrEwyktlPD21tLXKQZqjkh+Sw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792835475; h=DMARC-Filter:Received:Received:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition:In-Reply-To; bh=hvKkhPeqGlHLlvQVRL4+Bger2lswWQFcdJt0riLm0Oc=; b=GvsOqWXdc763uAVQgo3bqVBhY3ptIDBryrYEQgFSP2kjUO+TsaMIuJH0k2g/Au8tLYYl OTaf3BaIGnLEgejSTPzMOWjhE6otydlaAVCWuBphfp7bxKhGek9z1aD1zxygv2etXo4T/ Bt6atWtbP+9RkFcjW1jV9hbKP4u+t8ucl87/jWXJONVfhHRcUFLkaZTuGscXNyln+QqPo Z1ecQixtfMgBza18SfRnwOAaDgHxcGExFzZLBK0gV4EinRC/N7souYWspHf8QsddopS6Y alUJGSotlAeMI6ARBZAg1Dq63WwgtnwV2/6FsJ871wN+B2oEeq0Twatb8b/n/9UTqdw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none header.from=alpha.franken.de; spf=pass smtp.mailfrom=alpha.franken.de; arc=none smtp.remote-ip=193.175.24.41 Received: from elvis.franken.de (elvis.franken.de [193.175.24.41]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 56215606A31B; Sat, 24 Oct 2026 09:51:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 56215606A31B Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=alpha.franken.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=alpha.franken.de Received: from uucp by elvis.franken.de with local-rmail (Exim 3.36 #1) id 1xKYP8-0005Qd-00; Sat, 24 Oct 2026 11:51:10 +0200 Received: by alpha.franken.de (Postfix, from userid 1000) id 1D083C0423; Sat, 24 Oct 2026 11:51:01 +0200 (CEST) Date: Sat, 24 Oct 2026 11:51:01 +0200 From: Thomas Bogendoerfer To: "Maciej W. Rozycki" Cc: Imre Kaloz , linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] MIPS: SGI-IP27: Install the cache error vector on every CPU Message-ID: References: <20261021190253.30128-1-kaloz@kernel.org> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Oct 22, 2026 at 08:07:47PM +0100, Maciej W. Rozycki wrote: > On Wed, 21 Oct 2026, Imre Kaloz wrote: > > > diff --git a/arch/mips/sgi-ip27/ip27-smp.c b/arch/mips/sgi-ip27/ip27-smp.c > > index 62733e049570..0fef66b86959 100644 > > --- a/arch/mips/sgi-ip27/ip27-smp.c > > +++ b/arch/mips/sgi-ip27/ip27-smp.c > > @@ -133,6 +135,18 @@ static void ip27_init_cpu(void) > > per_cpu_init(); > > } > > > > +static void ip27_init_secondary(void) > > +{ > > + /* > > + * The hub flips the low 128K of the attribute 0 uncached alias per > > + * CPU slice and the cache error vector is fetched through that alias, > > + * so the copy trap_init() made through TO_UNCAC() only serves slice 0. > > + */ > > + memcpy((void *)CKSEG1ADDR(0x100), (void *)TO_UNCAC(0x100), 0x80); > > This just copies instructions between the same physical memory locations, > from an XKPHYS mapping to its corresponding KSEG1 mapping, i.e. the bus IP27 is special here: /* * IP27 uses the R10000's uncached attribute feature. Attribute 3 selects * uncached memory addressing. Hide the definitions on 32-bit compilation * of the compat-vdso code. */ #ifdef CONFIG_64BIT #define HSPEC_BASE _AC(0x9000000000000000, UL) #define IO_BASE _AC(0x9200000000000000, UL) #define MSPEC_BASE _AC(0x9400000000000000, UL) #define UNCAC_BASE _AC(0x9600000000000000, UL) #define CAC_BASE _AC(0xa800000000000000, UL) #endif Hub ASIC uses the extra address bits, so the physiacl address is not the same. Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]