From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 1/6] Use correct types to enable > 2G support Date: Fri, 01 Feb 2008 17:13:37 +0200 Message-ID: <47A33721.4020600@qumranet.com> References: <1201818980-27534-1-git-send-email-aliguori@us.ibm.com> <1201818980-27534-2-git-send-email-aliguori@us.ibm.com> <47A2F3C7.6060409@bellard.org> <47A32E40.3000204@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, Paul Brook , Fabrice Bellard , qemu-devel-qX2TKyscuCcdnm+yROfE0A@public.gmane.org To: Anthony Liguori Return-path: In-Reply-To: <47A32E40.3000204-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Anthony Liguori wrote: > Fabrice Bellard wrote: >> Anthony Liguori wrote: >>> + /* above 4giga memory allocation */ >>> + if (above_4g_mem_size > 0) { >>> + ram_addr = qemu_ram_alloc(above_4g_mem_size); >>> + cpu_register_physical_memory(0x100000000, >>> above_4g_mem_size, ram_addr); >>> + } >>> + >> >> Why do you need this ? All the RAM can be registered with a single >> call. I fear you need to do that because of KVM RAM handling >> limitations. > > On the x86, there is a rather large hole at the top of memory. > Currently, we do separate allocations around this whole. You can't > get away from doing multiple cpu_register_physical_memory calls here. > We've discussed just allocating a single chunk with qemu_ram_alloc > since so many places in QEMU assume that you can do phys_ram_base + PA. > > I think I'll change this too into a single qemu_ram_alloc. That will > fix the bug with KVM when using -kernel and large memory anyway :-) Won't that cause all of the memory in the hole to be wasted? You could munmap() it, but it's hardly elegant. -- Any sufficiently difficult bug is indistinguishable from a feature. ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/