Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2992487AbbEOVDB (ORCPT ); Fri, 15 May 2015 17:03:01 -0400 Received: from mailapp01.imgtec.com ([195.59.15.196]:30996 "EHLO mailapp01.imgtec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2992460AbbEOVC5 (ORCPT ); Fri, 15 May 2015 17:02:57 -0400 Message-ID: <55565EC0.9030102@imgtec.com> Date: Fri, 15 May 2015 14:01:52 -0700 From: Leonid Yegoshin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: David Daney CC: , , , , , , , , , , , Subject: Re: [PATCH v2] MIPS64: Support of at least 48 bits of SEGBITS References: <20150515013351.7450.12130.stgit@ubuntu-yegoshin> <55565BDF.6050503@gmail.com> In-Reply-To: <55565BDF.6050503@gmail.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.20.3.79] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1573 Lines: 47 On 05/15/2015 01:49 PM, David Daney wrote: > On 05/14/2015 06:34 PM, Leonid Yegoshin wrote: >> SEGBITS default is 40 bits or less, depending from CPU type. >> This patch introduces 48bits of application virtual address (SEGBITS) >> support. >> It is defined only for 16K and 64K pages and is optional (configurable). >> >> Penalty - a small number of additional pages for generic (small) >> applications. >> But for 64K pages it adds 3rd level of PTE structure, which has a little >> impact during software TLB refill. >> >> This patch is needed because MIPS I6XXX and P6XXX cores have 48 bit of >> virtual address in each segment (SEGBITS). >> > > Those processors don't require the patch. You wrote the patch to give > a larger VA space at the request of kernel users. So perhaps say: > > The patch (optionally) increases the VA space available to userspace > processes from N-bits to 48-bits > ... if CPU model supports that > >> >> +config 48VMBITS > > Should probabaly be called VABITS instead of VMBITS to match the terms > used in the architecture reference manuals, as well as other ports > (ARM64). > > Perhaps MIPS_VA_BITS_48 I don't mind here. It can be even called 48SEGBITS or so, to match arch manual more. MIPS Arch manual never says about VA bits but speaks about PABITS and SEGBITS. - Leonid. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/