Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751829Ab2FKRfh (ORCPT ); Mon, 11 Jun 2012 13:35:37 -0400 Received: from mail-lpp01m010-f46.google.com ([209.85.215.46]:59155 "EHLO mail-lpp01m010-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750905Ab2FKRfg convert rfc822-to-8bit (ORCPT ); Mon, 11 Jun 2012 13:35:36 -0400 MIME-Version: 1.0 In-Reply-To: <4FD5AFF2.3040306@cn.fujitsu.com> References: <4FD5AFF2.3040306@cn.fujitsu.com> From: Bjorn Helgaas Date: Mon, 11 Jun 2012 10:35:13 -0700 Message-ID: Subject: Re: [PATCH 1/2 v2] x86: add max_addr boot option To: Wen Congyang Cc: rob@landley.net, tglx@linutronix.de, Ingo Molnar , x86@kernel.org, "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4545 Lines: 118 On Mon, Jun 11, 2012 at 1:44 AM, Wen Congyang wrote: > Currently, the boot option max_addr is only supported on ia64 platform. > We also need it on x86 platform. > For example: > There are two nodes: > ?NODE#0 ?address range 0x00000000 00000000 - 0x00010000 00000000 > ?NODE#1 ?address range 0x00010000 00000000 - 0x00020000 00000000 > If we only want to use node0, we can specify the max_addr. The boot > option "mem=" can do the same thing now. But the boot option "mem=" > means the total memory used by the system. If we tell the user > that the boot option "mem=" can do this, it will confuse the user. > So we need an new boot option "max_addr" on x86 platform. I don't object to this patch (and thanks for tweaking the mem range printk). I don't know what your use case is, but from a user interface perspective, the "max_addr=" option feels like a bit of a hack. If you're trying to avoid use of other nodes, "max_addr" is an awkward way to do it. It requires the user to know the physical address -> node mappings, and it doesn't affect the CPUs and I/O resources on other nodes. You could implement a "numa_node=" or similar parameter that would allow you to ignore remote memory, CPUs, and I/O. > Signed-off-by: Wen Congyang > --- > ?Documentation/kernel-parameters.txt | ? ?2 +- > ?arch/x86/kernel/e820.c ? ? ? ? ? ? ?| ? 36 +++++++++++++++++++++++++++++++++++ > ?2 files changed, 37 insertions(+), 1 deletions(-) > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > index a92c5eb..034609d 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -1441,7 +1441,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted. > ? ? ? ? ? ? ? ? ? ? ? ? yeeloong laptop. > ? ? ? ? ? ? ? ? ? ? ? ?Example: machtype=lemote-yeeloong-2f-7inch > > - ? ? ? max_addr=nn[KMG] ? ? ? ?[KNL,BOOT,ia64] All physical memory greater > + ? ? ? max_addr=nn[KMG] ? ? ? ?[KNL,BOOT,ia64,X86] All physical memory greater > ? ? ? ? ? ? ? ? ? ? ? ?than or equal to this physical address is ignored. > > ? ? ? ?maxcpus= ? ? ? ?[SMP] Maximum number of processors that an SMP kernel > diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c > index 4185797..cd07226 100644 > --- a/arch/x86/kernel/e820.c > +++ b/arch/x86/kernel/e820.c > @@ -47,6 +47,7 @@ unsigned long pci_mem_start = 0xaeedbabe; > ?#ifdef CONFIG_PCI > ?EXPORT_SYMBOL(pci_mem_start); > ?#endif > +static u64 max_addr = ~0ULL; > > ?/* > ?* This function checks if any part of the range is mapped > @@ -119,6 +120,20 @@ static void __init __e820_add_region(struct e820map *e820x, u64 start, u64 size, > ? ? ? ? ? ? ? ?return; > ? ? ? ?} > > + ? ? ? if (start >= max_addr) { > + ? ? ? ? ? ? ? printk(KERN_ERR "e820: ignoring [mem %#010llx-%#010llx]\n", > + ? ? ? ? ? ? ? ? ? ? ?(unsigned long long)start, > + ? ? ? ? ? ? ? ? ? ? ?(unsigned long long)(start + size - 1)); > + ? ? ? ? ? ? ? return; > + ? ? ? } > + > + ? ? ? if (max_addr - start < size) { > + ? ? ? ? ? ? ? printk(KERN_ERR "e820: ignoring [mem %#010llx-%#010llx]\n", > + ? ? ? ? ? ? ? ? ? ? ?(unsigned long long)max_addr, > + ? ? ? ? ? ? ? ? ? ? ?(unsigned long long)(start + size - 1)); > + ? ? ? ? ? ? ? size = max_addr - start; > + ? ? ? } > + > ? ? ? ?e820x->map[x].addr = start; > ? ? ? ?e820x->map[x].size = size; > ? ? ? ?e820x->map[x].type = type; > @@ -835,6 +850,22 @@ static int __init parse_memopt(char *p) > ?} > ?early_param("mem", parse_memopt); > > +static int __init parse_memmax_opt(char *p) > +{ > + ? ? ? char *oldp; > + > + ? ? ? if (!p) > + ? ? ? ? ? ? ? return -EINVAL; > + > + ? ? ? oldp = p; > + ? ? ? max_addr = memparse(p, &p); > + ? ? ? if (p == oldp) > + ? ? ? ? ? ? ? return -EINVAL; > + > + ? ? ? return 0; > +} > +early_param("max_addr", parse_memmax_opt); > + > ?static int __init parse_memmap_opt(char *p) > ?{ > ? ? ? ?char *oldp; > @@ -881,6 +912,11 @@ early_param("memmap", parse_memmap_opt); > > ?void __init finish_e820_parsing(void) > ?{ > + ? ? ? if (max_addr != ~0ULL) { > + ? ? ? ? ? ? ? userdef = 1; > + ? ? ? ? ? ? ? e820_remove_range(max_addr, ULLONG_MAX - max_addr, E820_RAM, 1); > + ? ? ? } > + > ? ? ? ?if (userdef) { > ? ? ? ? ? ? ? ?u32 nr = e820.nr_map; > > -- > 1.7.1 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/