From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ob0-f176.google.com (mail-ob0-f176.google.com [209.85.214.176]) by kanga.kvack.org (Postfix) with ESMTP id 239B86B0085 for ; Mon, 3 Nov 2014 20:04:36 -0500 (EST) Received: by mail-ob0-f176.google.com with SMTP id va2so9892185obc.7 for ; Mon, 03 Nov 2014 17:04:35 -0800 (PST) Received: from g4t3426.houston.hp.com (g4t3426.houston.hp.com. [15.201.208.54]) by mx.google.com with ESMTPS id g5si19830107oed.11.2014.11.03.17.04.34 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Mon, 03 Nov 2014 17:04:34 -0800 (PST) Message-ID: <1415062233.10958.42.camel@misato.fc.hp.com> Subject: Re: [PATCH v4 4/7] x86, mm, pat: Add pgprot_writethrough() for WT From: Toshi Kani Date: Mon, 03 Nov 2014 17:50:33 -0700 In-Reply-To: References: <1414450545-14028-1-git-send-email-toshi.kani@hp.com> <1414450545-14028-5-git-send-email-toshi.kani@hp.com> <94D0CD8314A33A4D9D801C0FE68B4029593578ED@G9W0745.americas.hpqcorp.net> <1415052905.10958.39.camel@misato.fc.hp.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Thomas Gleixner Cc: "Elliott, Robert (Server Storage)" , "hpa@zytor.com" , "mingo@redhat.com" , "akpm@linux-foundation.org" , "arnd@arndb.de" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "jgross@suse.com" , "stefan.bader@canonical.com" , "luto@amacapital.net" , "hmh@hmh.eng.br" , "yigal@plexistor.com" , "konrad.wilk@oracle.com" On Mon, 2014-11-03 at 23:53 +0100, Thomas Gleixner wrote: > On Mon, 3 Nov 2014, Toshi Kani wrote: > > On Mon, 2014-11-03 at 22:10 +0000, Elliott, Robert (Server Storage) > > wrote: > > : > > > > Subject: [PATCH v4 4/7] x86, mm, pat: Add pgprot_writethrough() for > > > > WT > > > > > > > > This patch adds pgprot_writethrough() for setting WT to a given > > > > pgprot_t. > > > > > > > > Signed-off-by: Toshi Kani > > > > Reviewed-by: Konrad Rzeszutek Wilk > > > ... > > > > diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c > > > > index a214f5a..a0264d3 100644 > > > > --- a/arch/x86/mm/pat.c > > > > +++ b/arch/x86/mm/pat.c > > > > @@ -896,6 +896,16 @@ pgprot_t pgprot_writecombine(pgprot_t prot) > > > > } > > > > EXPORT_SYMBOL_GPL(pgprot_writecombine); > > > > > > > > +pgprot_t pgprot_writethrough(pgprot_t prot) > > > > +{ > > > > + if (pat_enabled) > > > > + return __pgprot(pgprot_val(prot) | > > > > + cachemode2protval(_PAGE_CACHE_MODE_WT)); > > > > + else > > > > + return pgprot_noncached(prot); > > > > +} > > > > +EXPORT_SYMBOL_GPL(pgprot_writethrough); > > > ... > > > > > > Would you be willing to use EXPORT_SYMBOL for the new > > > pgprot_writethrough function to provide more flexibility > > > for modules to utilize the new feature? In x86/mm, 18 of 60 > > > current exports are GPL and 42 are not GPL. > > > > I simply used EXPORT_SYMBOL_GPL() since pgprot_writecombine() used > > it. :-) This interface is intended to be used along with > > remap_pfn_range() and ioremap_prot(), which are both exported with > > EXPORT_SYMBOL(). So, it seems reasonable to export it with > > EXPORT_SYMBOL() as well. I will make this change. > > NAK. > > This is new functionality and we really have no reason to give the GPL > circumventors access to it. Thanks for the background info about EXPORT_SYMBOL. I will keep it no change. -Toshi -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org