From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eugene Fedotov Subject: Re: [PATCH RESEND v5 2/6] xen/arm: Implement get_maximum_gpfn hypercall for arm Date: Tue, 19 Nov 2013 16:35:00 +0400 Message-ID: <528B5AF4.9070901@samsung.com> References: <1383897048-12528-1-git-send-email-jaeyong.yoo@samsung.com> <1383897048-12528-3-git-send-email-jaeyong.yoo@samsung.com> <1384269717.10204.45.camel@kazak.uk.xensource.com> <5283382C.9040004@samsung.com> <1384340304.5406.58.camel@kazak.uk.xensource.com> <5285C797.9010309@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-reply-to: <5285C797.9010309@samsung.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: xen-devel@lists.xen.org, Ian Campbell List-Id: xen-devel@lists.xenproject.org 15.11.2013 11:04, Eugene Fedotov wrote: > 13.11.2013 14:58, Ian Campbell wrote: >> On Wed, 2013-11-13 at 12:28 +0400, Eugene Fedotov wrote: >>>>> diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c >>>>> index 123280e..3801f07 100644 >>>>> --- a/xen/arch/arm/mm.c >>>>> +++ b/xen/arch/arm/mm.c >>>>> @@ -927,7 +927,11 @@ int page_is_ram_type(unsigned long mfn, >>>>> unsigned long mem_type) >>>>> unsigned long domain_get_maximum_gpfn(struct domain *d) >>>> s/unsigned long/xen_pfn_t/ I think. >>>> >>>> Urk, which will break the ABI for this hypercall. That's something >>>> of a >>>> conundrum :-/ >>>> >>>> It is a domctl so we are at liberty to change it, probably to taking a >>>> xen_pfn_t * to fill in instead of returning the value. >>>> >>>> I'm in two minds about whether we should do so now or postpone it >>>> (which >>>> risks forgetting and having an obscure bug somewhere down the line). >>> OK, this way, or other solution is to purge this hypercall yet in >>> migration and use max_memkb field in DOMCTL_getdomaininfo to obtain the >>> maximum PFN. >> Is there an interface to retrieve that? I don't see it :-( No, it is another hypercall XEN_DOMCTL_getdomaininfo. max_memkb field in xc_dominfo_t structure is a second way to retrieve maximum memory size and calculate PFN. Do we need domain_get_maximum_gpfn ? In addition to this question I need to ask why we need xen_pfn_t (that is always 64 bit on Xen-arm) for physical memory PFN. Currently the following libxc proxies for DOMCTL: xc_domain_setmaxmem and max_memkb field in xc_domain_getinfo() are working with unsigned long max_mem_kb parameter (that is 32 bit for ARM32) In case if 64 bit PFN is needed, xen_pfn_t returning hypercall looks like better then xc_domain_getinfo() . Best regards, Evgeny.