From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [PATCH -mm -v4 1/3] i386/x86_64 boot: setup data From: "Huang, Ying" In-Reply-To: <200710090125.27263.nickpiggin@yahoo.com.au> References: <1191912010.9719.18.camel@caritas-dev.intel.com> <200710090125.27263.nickpiggin@yahoo.com.au> Content-Type: text/plain Content-Transfer-Encoding: 7bit Date: Tue, 09 Oct 2007 16:22:19 +0800 Message-Id: <1191918139.9719.47.camel@caritas-dev.intel.com> Mime-Version: 1.0 Sender: owner-linux-mm@kvack.org Return-Path: To: Nick Piggin Cc: linux-mm@kvack.org, "H. Peter Anvin" , Andi Kleen , "Eric W. Biederman" , akpm@linux-foundation.org, Yinghai Lu , Chandramouli Narayanan , linux-kernel@vger.kernel.org List-ID: On Tue, 2007-10-09 at 01:25 +1000, Nick Piggin wrote: > On Tuesday 09 October 2007 16:40, Huang, Ying wrote: > > > +unsigned long copy_from_phys(void *to, unsigned long from_phys, > > + unsigned long n) > > +{ > > + struct page *page; > > + void *from; > > + unsigned long remain = n, offset, trunck; > > + > > + while (remain) { > > + page = pfn_to_page(from_phys >> PAGE_SHIFT); > > + from = kmap_atomic(page, KM_USER0); > > + offset = from_phys & ~PAGE_MASK; > > + if (remain > PAGE_SIZE - offset) > > + trunck = PAGE_SIZE - offset; > > + else > > + trunck = remain; > > + memcpy(to, from + offset, trunck); > > + kunmap_atomic(from, KM_USER0); > > + to += trunck; > > + from_phys += trunck; > > + remain -= trunck; > > + } > > + return n; > > +} > > > I suppose that's not unreasonable to put in mm/memory.c, although > it's not really considered a problem to do this kind of stuff in > a low level arch file... > > You have no kernel virtual mapping for the source data? > On 32-bit platform such as i386. Some memory zones have no kernel virtual mapping (highmem region etc). So I think this may be useful as a universal way to access physical memory. But it can be more efficient to implement it in arch file for some arch. Should this implementation be used as a fall back implementation with attribute "weak"? > Should it be __init? > > Care to add a line of documentation if you keep it in mm/memory.c? > OK, I will add the document in the next version. Best Regards, Huang Ying -- 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