From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: [PATCH 1/5] xen: use maximum reservation to limit amount of usable RAM Date: Wed, 31 Aug 2011 16:40:57 -0400 Message-ID: <20110831204057.GA641@dumpdata.com> References: <1313765840-22084-1-git-send-email-david.vrabel@citrix.com> <1313765840-22084-2-git-send-email-david.vrabel@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1313765840-22084-2-git-send-email-david.vrabel@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: David Vrabel Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org > Signed-off-by: David Vrabel > --- > arch/x86/xen/setup.c | 19 +++++++++++++++++++ > 1 files changed, 19 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c > index df118a8..c3b8d44 100644 > --- a/arch/x86/xen/setup.c > +++ b/arch/x86/xen/setup.c > @@ -184,6 +184,19 @@ static unsigned long __init xen_set_identity(const struct e820entry *list, > PFN_UP(start_pci), PFN_DOWN(last)); > return identity; > } > + > +static unsigned long __init xen_get_max_pages(void) > +{ > + unsigned long max_pages = MAX_DOMAIN_PAGES; > + domid_t domid = DOMID_SELF; > + int ret; > + > + ret = HYPERVISOR_memory_op(XENMEM_maximum_reservation, &domid); > + if (ret > 0) > + max_pages = ret; > + return min(max_pages, MAX_DOMAIN_PAGES); > +} > + > /** > * machine_specific_memory_setup - Hook for machine specific memory setup. > **/ > @@ -292,6 +305,12 @@ char * __init xen_memory_setup(void) > > sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map); > > + extra_limit = xen_get_max_pages(); > + if (extra_limit >= max_pfn) > + extra_pages = extra_limit - max_pfn; > + else > + extra_pages = 0; > + > extra_pages += xen_return_unused_memory(xen_start_info->nr_pages, &e820); I ran this on three setups: 1) PV (domU) 2) PV+PCI (dom0) 3) PV+PCI+e820_hole=1 (domU) and then the same without this patch. Both the 2) and 3) worked correctly - the E820 had the same non-RAM regions and gaps - and the last RAM E820 entry was properly truncated. However, when it came to pure PV it was truncated more than it should: domU: domU: 0000000000000000 - 00000000000a0000 (usable) 0000000000000000 - 00000000000a0000 (usable) 00000000000a0000 - 0000000000100000 (reserved) 00000000000a0000 - 0000000000100000 (reserved) 0000000000100000 - 0000000040800000 (usable) | 0000000000100000 - 0000000040100000 (usable) (left has the old PV - without your patch). Which makes me think that there is something amiss in the toolstack? I used 'xl' (latest xen-unstable from today).