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[PATCH 32/35] use nr_cpus= to set nr_cpu_ids early

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Yinghai Lu

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Feb 9, 2010, 2:40:02 PM2/9/10
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on x86, before prefill_possible_map(), nr_cpu_ids will be NR_CPUS aka CONFIG_NR_CPUS

add nr_cpus= to set nr_cpu_ids. so we can simulate cpus <=8 are installed on
normal config.

-v2: accordging to Christoph, acpi_numa_init should use nr_cpu_ids in stead of
NR_CPUS.

Signed-off-by: Yinghai Lu <yin...@kernel.org>
Acked-by: Linus Torvalds <torv...@linux-foundation.org>
---
arch/ia64/kernel/acpi.c | 4 ++--
arch/x86/kernel/smpboot.c | 7 ++++---
drivers/acpi/numa.c | 4 ++--
init/main.c | 14 ++++++++++++++
4 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/arch/ia64/kernel/acpi.c b/arch/ia64/kernel/acpi.c
index 40574ae..605a08b 100644
--- a/arch/ia64/kernel/acpi.c
+++ b/arch/ia64/kernel/acpi.c
@@ -881,8 +881,8 @@ __init void prefill_possible_map(void)

possible = available_cpus + additional_cpus;

- if (possible > NR_CPUS)
- possible = NR_CPUS;
+ if (possible > nr_cpu_ids)
+ possible = nr_cpu_ids;

printk(KERN_INFO "SMP: Allowing %d CPUs, %d hotplug CPUs\n",
possible, max((possible - available_cpus), 0));
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index b2ebcba..6c69693 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1217,11 +1217,12 @@ __init void prefill_possible_map(void)

total_cpus = max_t(int, possible, num_processors + disabled_cpus);

- if (possible > CONFIG_NR_CPUS) {
+ /* nr_cpu_ids could be reduced via nr_cpus= */
+ if (possible > nr_cpu_ids) {
printk(KERN_WARNING
"%d Processors exceeds NR_CPUS limit of %d\n",
- possible, CONFIG_NR_CPUS);
- possible = CONFIG_NR_CPUS;
+ possible, nr_cpu_ids);
+ possible = nr_cpu_ids;
}

printk(KERN_INFO "SMP: Allowing %d CPUs, %d hotplug CPUs\n",
diff --git a/drivers/acpi/numa.c b/drivers/acpi/numa.c
index 7ad48df..b872546 100644
--- a/drivers/acpi/numa.c
+++ b/drivers/acpi/numa.c
@@ -279,9 +279,9 @@ int __init acpi_numa_init(void)
/* SRAT: Static Resource Affinity Table */
if (!acpi_table_parse(ACPI_SIG_SRAT, acpi_parse_srat)) {
acpi_table_parse_srat(ACPI_SRAT_TYPE_X2APIC_CPU_AFFINITY,
- acpi_parse_x2apic_affinity, NR_CPUS);
+ acpi_parse_x2apic_affinity, nr_cpu_ids);
acpi_table_parse_srat(ACPI_SRAT_TYPE_CPU_AFFINITY,
- acpi_parse_processor_affinity, NR_CPUS);
+ acpi_parse_processor_affinity, nr_cpu_ids);
ret = acpi_table_parse_srat(ACPI_SRAT_TYPE_MEMORY_AFFINITY,
acpi_parse_memory_affinity,
NR_NODE_MEMBLKS);
diff --git a/init/main.c b/init/main.c
index 8451878..05b5283 100644
--- a/init/main.c
+++ b/init/main.c
@@ -149,6 +149,20 @@ static int __init nosmp(char *str)

early_param("nosmp", nosmp);

+/* this is hard limit */
+static int __init nrcpus(char *str)
+{
+ int nr_cpus;
+
+ get_option(&str, &nr_cpus);
+ if (nr_cpus > 0 && nr_cpus < nr_cpu_ids)
+ nr_cpu_ids = nr_cpus;
+
+ return 0;
+}
+
+early_param("nr_cpus", nrcpus);
+
static int __init maxcpus(char *str)
{
get_option(&str, &setup_max_cpus);
--
1.6.4.2

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Yinghai Lu

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Feb 9, 2010, 2:40:03 PM2/9/10
to
let's make 32bit consistent with 64bit

Signed-off-by: Yinghai Lu <yin...@kernel.org>
---
arch/x86/Kconfig | 1 -
arch/x86/kernel/early_res.c | 3 +++
arch/x86/mm/init_32.c | 6 ++++++
arch/x86/mm/numa_32.c | 3 +++
4 files changed, 12 insertions(+), 1 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index a6fedb8..24c2908 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -571,7 +571,6 @@ config PARAVIRT_DEBUG
config NO_BOOTMEM
default y
bool "Disable Bootmem code"
- depends on X86_64
---help---
use early_res directly instead of bootmem before slab is ready.

diff --git a/arch/x86/kernel/early_res.c b/arch/x86/kernel/early_res.c
index 52804e9..38a0c61 100644
--- a/arch/x86/kernel/early_res.c
+++ b/arch/x86/kernel/early_res.c
@@ -354,6 +354,9 @@ int __init get_free_all_memory_range(struct range **rangep, int nodeid)

/* need to go over early_node_map to find out good range for node */
nr_range = add_from_early_node_map(range, count, nr_range, nodeid);
+#ifdef CONFIG_X86_32
+ subtract_range(range, count, max_low_pfn, -1UL);
+#endif
subtract_early_res(range, count);
nr_range = clean_sort_range(range, count);

diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 2dccde0..262867a 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -748,6 +748,7 @@ static void __init zone_sizes_init(void)
free_area_init_nodes(max_zone_pfns);
}

+#ifndef CONFIG_NO_BOOTMEM
static unsigned long __init setup_node_bootmem(int nodeid,
unsigned long start_pfn,
unsigned long end_pfn,
@@ -767,9 +768,11 @@ static unsigned long __init setup_node_bootmem(int nodeid,

return bootmap + bootmap_size;
}
+#endif

void __init setup_bootmem_allocator(void)
{
+#ifndef CONFIG_NO_BOOTMEM
int nodeid;
unsigned long bootmap_size, bootmap;
/*
@@ -781,11 +784,13 @@ void __init setup_bootmem_allocator(void)
if (bootmap == -1L)
panic("Cannot find bootmem map of size %ld\n", bootmap_size);
reserve_early(bootmap, bootmap + bootmap_size, "BOOTMAP");
+#endif

printk(KERN_INFO " mapped low ram: 0 - %08lx\n",
max_pfn_mapped<<PAGE_SHIFT);
printk(KERN_INFO " low ram: 0 - %08lx\n", max_low_pfn<<PAGE_SHIFT);

+#ifndef CONFIG_NO_BOOTMEM
for_each_online_node(nodeid) {
unsigned long start_pfn, end_pfn;

@@ -803,6 +808,7 @@ void __init setup_bootmem_allocator(void)
bootmap = setup_node_bootmem(nodeid, start_pfn, end_pfn,
bootmap);
}
+#endif

after_bootmem = 1;
}
diff --git a/arch/x86/mm/numa_32.c b/arch/x86/mm/numa_32.c
index b20760c..809baaa 100644
--- a/arch/x86/mm/numa_32.c
+++ b/arch/x86/mm/numa_32.c
@@ -418,7 +418,10 @@ void __init initmem_init(unsigned long start_pfn, unsigned long end_pfn,

for_each_online_node(nid) {
memset(NODE_DATA(nid), 0, sizeof(struct pglist_data));
+ NODE_DATA(nid)->node_id = nid;
+#ifndef CONFIG_NO_BOOTMEM
NODE_DATA(nid)->bdata = &bootmem_node_data[nid];
+#endif
}

setup_bootmem_allocator();

Andrew Morton

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Feb 9, 2010, 3:10:02 PM2/9/10
to
On Tue, 09 Feb 2010 11:32:43 -0800
Yinghai Lu <yin...@kernel.org> wrote:

> +early_param("nr_cpus", nrcpus);

Please document kernel boot parameters in Documentation/kernel-parameters.txt.

Andrew Morton

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Feb 9, 2010, 3:10:02 PM2/9/10
to
On Tue, 09 Feb 2010 11:32:34 -0800
Yinghai Lu <yin...@kernel.org> wrote:

> --- a/arch/x86/kernel/early_res.c
> +++ b/arch/x86/kernel/early_res.c
> @@ -354,6 +354,9 @@ int __init get_free_all_memory_range(struct range **rangep, int nodeid)
>
> /* need to go over early_node_map to find out good range for node */
> nr_range = add_from_early_node_map(range, count, nr_range, nodeid);
> +#ifdef CONFIG_X86_32
> + subtract_range(range, count, max_low_pfn, -1UL);
> +#endif
> subtract_early_res(range, count);
> nr_range = clean_sort_range(range, count);

I'm too lazy to hunt through all the patches to see the surrounding code...

The "-1UL" is worrisome. If that contant is to be assigned to a u64
then on x86_32 we end up with 0x00000000ffffffff, which is surely
wrong.

Generally I think it's safer and more maintainable (but odd-looking) to
use plain old "-1" when specifying the all-ones contant pattern.
Because "-1" always works, whatever the size of the target scalar.
This particularly matters when you're dealing with types which have
different sizes on different architectures, or whose type changes with
config options.

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