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Message-ID: <AANLkTi=koyyz8h1A3qWbp2F+N3kA46rJfHPSPN+Ms8hm@mail.gmail.com> Date: Mon, 7 Feb 2011 21:09:50 -0800 From: Yinghai Lu <yinghai@...nel.org> To: Jeremy Fitzhardinge <jeremy@...p.org> Cc: Stefano Stabellini <stefano.stabellini@...citrix.com>, "H. Peter Anvin" <hpa@...or.com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "tglx@...utronix.de" <tglx@...utronix.de>, "x86@...nel.org" <x86@...nel.org>, Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>, Jan Beulich <JBeulich@...ell.com> Subject: Re: [PATCH] x86/mm/init: respect memblock reserved regions when destroying mappings On Mon, Feb 7, 2011 at 8:56 PM, Jeremy Fitzhardinge <jeremy@...p.org> wrote: > On 02/07/2011 07:12 PM, Yinghai Lu wrote: >> On 02/07/2011 01:56 PM, Jeremy Fitzhardinge wrote: >>> On 02/07/2011 11:00 AM, Yinghai Lu wrote: >>>> On 02/07/2011 10:58 AM, Stefano Stabellini wrote: >>>>> On Mon, 7 Feb 2011, Yinghai Lu wrote: >>>>>> On 02/07/2011 08:50 AM, Stefano Stabellini wrote: >>>>>>> On Sun, 6 Feb 2011, Yinghai Lu wrote: >>>>>>>> On 02/05/2011 11:30 PM, H. Peter Anvin wrote: >>>>>>>>> On 02/05/2011 11:02 PM, Yinghai Lu wrote: >>>>>>>>>> why not just move calling cleanup_highmap down? >>>>>>>>>> >>>>>>>>>> something like attached patch. >>>>>>>>> This patch looks very clean and looks on the surface of it like it is >>>>>>>>> removing some ugly ad hoc code, but (as always) it needs a description >>>>>>>>> about the problem it solves and why it is correct. >>>>>>>> Sure. >>>>>>>> >>>>>>>> >>>>>>>> Jeremy and xen guys, can you please check if it works well with xen ? >>>>>>>> >>>>>>> Actually this patch makes things worse on xen, because before >>>>>>> cleanup_highmap() wasn't called at all on xen (on purpose) and now it >>>>>>> is, fully destroying all the mappings we have at _end. >>>>>>> >>>>>>> Can we add a check on memblock reserved regions in cleanup_highmap()? >>>>>>> Otherwise could we avoid calling cleanup_highmap() at all on xen? >>>>>> why DO xen need over-mapped kernel initial mapping? >>>>>> >>>>>> what is in that range after _end to 512M? >>>>> The mfn list that is the list of machine frame numbers assigned to this >>>>> domain; it is used across the kernel to convert pfns into mfns. >>>>> It passed to us at that address by the domain builder. >>>> is it possible for you to pass physical address, and then map it in kernel? >>> That is possible in principle, but very difficult in practice. >>> >>> What's wrong with honouring reserved memory ranges under all circumstances? >> why punishing native path with those checking? > > Why is it punishing anyone to expect memory reservations to be observed? > >> please check if >> >> + * max_pfn_mapped is set to KERNEL_IMAGE_SIZE >> PAGE_SHIFT in >> + * head64.c::x86_start_kernel(), aka native path >> + */ >> + if (max_pfn_mapped != (KERNEL_IMAGE_SIZE >> PAGE_SHIFT)) >> + return; >> >> could be used to skip clear highmap for xen path? > > Seems pretty ad-hoc. > then what is size for mfn-list after _end... could be copied or move to BRK. Yinghai -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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