Messages in this thread | | | From | Bjorn Helgaas <> | Date | Mon, 11 Jun 2012 10:35:13 -0700 | Subject | Re: [PATCH 1/2 v2] x86: add max_addr boot option |
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On Mon, Jun 11, 2012 at 1:44 AM, Wen Congyang <wency@cn.fujitsu.com> 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 <wency@cn.fujitsu.com> > --- > 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 <start,end> 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/
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