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Message-Id: <20231012024842.99703-5-rongwei.wang@linux.alibaba.com>
Date: Thu, 12 Oct 2023 10:48:41 +0800
From: Rongwei Wang <rongwei.wang@...ux.alibaba.com>
To: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-mm@...ck.org
Cc: akpm@...ux-foundation.org, willy@...radead.org,
catalin.marinas@....com, dave.hansen@...ux.intel.com,
tj@...nel.org, mingo@...hat.com
Subject: [PATCH RFC 4/5] mm/numa: support CONFIG_NUMA_EMU for arm64
The CONFIG_NUMA_EMU migrates from x86/Kconfig
to mm/Kconfig. Now x86 and arm64 support it.
Signed-off-by: Rongwei Wang <rongwei.wang@...ux.alibaba.com>
---
arch/x86/Kconfig | 8 -
arch/x86/mm/Makefile | 1 -
arch/x86/mm/numa_emulation.c | 585 -----------------------------------
drivers/base/arch_numa.c | 3 +
include/asm-generic/numa.h | 12 +
mm/Kconfig | 8 +
mm/numa.c | 12 +
7 files changed, 35 insertions(+), 594 deletions(-)
delete mode 100644 arch/x86/mm/numa_emulation.c
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 66bfabae8814..13438bfe2ec1 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1568,14 +1568,6 @@ config X86_64_ACPI_NUMA
help
Enable ACPI SRAT based node topology detection.
-config NUMA_EMU
- bool "NUMA emulation"
- depends on NUMA
- help
- Enable NUMA emulation. A flat machine will be split
- into virtual nodes when booted with "numa=fake=N", where N is the
- number of nodes. This is only useful for debugging.
-
config NODES_SHIFT
int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
range 1 10
diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile
index c80febc44cd2..1581f17e5de4 100644
--- a/arch/x86/mm/Makefile
+++ b/arch/x86/mm/Makefile
@@ -56,7 +56,6 @@ obj-$(CONFIG_MMIOTRACE_TEST) += testmmiotrace.o
obj-$(CONFIG_NUMA) += numa.o numa_$(BITS).o
obj-$(CONFIG_AMD_NUMA) += amdtopology.o
obj-$(CONFIG_ACPI_NUMA) += srat.o
-obj-$(CONFIG_NUMA_EMU) += numa_emulation.o
obj-$(CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS) += pkeys.o
obj-$(CONFIG_RANDOMIZE_MEMORY) += kaslr.o
diff --git a/arch/x86/mm/numa_emulation.c b/arch/x86/mm/numa_emulation.c
deleted file mode 100644
index 9a9305367fdd..000000000000
--- a/arch/x86/mm/numa_emulation.c
+++ /dev/null
@@ -1,585 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * NUMA emulation
- */
-#include <linux/kernel.h>
-#include <linux/errno.h>
-#include <linux/topology.h>
-#include <linux/memblock.h>
-#include <asm/dma.h>
-
-#include "numa_internal.h"
-
-static int emu_nid_to_phys[MAX_NUMNODES];
-static char *emu_cmdline __initdata;
-
-int __init numa_emu_cmdline(char *str)
-{
- emu_cmdline = str;
- return 0;
-}
-
-static int __init emu_find_memblk_by_nid(int nid, const struct numa_meminfo *mi)
-{
- int i;
-
- for (i = 0; i < mi->nr_blks; i++)
- if (mi->blk[i].nid == nid)
- return i;
- return -ENOENT;
-}
-
-static u64 __init mem_hole_size(u64 start, u64 end)
-{
- unsigned long start_pfn = PFN_UP(start);
- unsigned long end_pfn = PFN_DOWN(end);
-
- if (start_pfn < end_pfn)
- return PFN_PHYS(absent_pages_in_range(start_pfn, end_pfn));
- return 0;
-}
-
-/*
- * Sets up nid to range from @start to @end. The return value is -errno if
- * something went wrong, 0 otherwise.
- */
-static int __init emu_setup_memblk(struct numa_meminfo *ei,
- struct numa_meminfo *pi,
- int nid, int phys_blk, u64 size)
-{
- struct numa_memblk *eb = &ei->blk[ei->nr_blks];
- struct numa_memblk *pb = &pi->blk[phys_blk];
-
- if (ei->nr_blks >= NR_NODE_MEMBLKS) {
- pr_err("NUMA: Too many emulated memblks, failing emulation\n");
- return -EINVAL;
- }
-
- ei->nr_blks++;
- eb->start = pb->start;
- eb->end = pb->start + size;
- eb->nid = nid;
-
- if (emu_nid_to_phys[nid] == NUMA_NO_NODE)
- emu_nid_to_phys[nid] = pb->nid;
-
- pb->start += size;
- if (pb->start >= pb->end) {
- WARN_ON_ONCE(pb->start > pb->end);
- numa_remove_memblk_from(phys_blk, pi);
- }
-
- printk(KERN_INFO "Faking node %d at [mem %#018Lx-%#018Lx] (%LuMB)\n",
- nid, eb->start, eb->end - 1, (eb->end - eb->start) >> 20);
- return 0;
-}
-
-/*
- * Sets up nr_nodes fake nodes interleaved over physical nodes ranging from addr
- * to max_addr.
- *
- * Returns zero on success or negative on error.
- */
-static int __init split_nodes_interleave(struct numa_meminfo *ei,
- struct numa_meminfo *pi,
- u64 addr, u64 max_addr, int nr_nodes)
-{
- nodemask_t physnode_mask = numa_nodes_parsed;
- u64 size;
- int big;
- int nid = 0;
- int i, ret;
-
- if (nr_nodes <= 0)
- return -1;
- if (nr_nodes > MAX_NUMNODES) {
- pr_info("numa=fake=%d too large, reducing to %d\n",
- nr_nodes, MAX_NUMNODES);
- nr_nodes = MAX_NUMNODES;
- }
-
- /*
- * Calculate target node size. x86_32 freaks on __udivdi3() so do
- * the division in ulong number of pages and convert back.
- */
- size = max_addr - addr - mem_hole_size(addr, max_addr);
- size = PFN_PHYS((unsigned long)(size >> PAGE_SHIFT) / nr_nodes);
-
- /*
- * Calculate the number of big nodes that can be allocated as a result
- * of consolidating the remainder.
- */
- big = ((size & ~FAKE_NODE_MIN_HASH_MASK) * nr_nodes) /
- FAKE_NODE_MIN_SIZE;
-
- size &= FAKE_NODE_MIN_HASH_MASK;
- if (!size) {
- pr_err("Not enough memory for each node. "
- "NUMA emulation disabled.\n");
- return -1;
- }
-
- /*
- * Continue to fill physical nodes with fake nodes until there is no
- * memory left on any of them.
- */
- while (!nodes_empty(physnode_mask)) {
- for_each_node_mask(i, physnode_mask) {
- u64 dma32_end = PFN_PHYS(MAX_DMA32_PFN);
- u64 start, limit, end;
- int phys_blk;
-
- phys_blk = emu_find_memblk_by_nid(i, pi);
- if (phys_blk < 0) {
- node_clear(i, physnode_mask);
- continue;
- }
- start = pi->blk[phys_blk].start;
- limit = pi->blk[phys_blk].end;
- end = start + size;
-
- if (nid < big)
- end += FAKE_NODE_MIN_SIZE;
-
- /*
- * Continue to add memory to this fake node if its
- * non-reserved memory is less than the per-node size.
- */
- while (end - start - mem_hole_size(start, end) < size) {
- end += FAKE_NODE_MIN_SIZE;
- if (end > limit) {
- end = limit;
- break;
- }
- }
-
- /*
- * If there won't be at least FAKE_NODE_MIN_SIZE of
- * non-reserved memory in ZONE_DMA32 for the next node,
- * this one must extend to the boundary.
- */
- if (end < dma32_end && dma32_end - end -
- mem_hole_size(end, dma32_end) < FAKE_NODE_MIN_SIZE)
- end = dma32_end;
-
- /*
- * If there won't be enough non-reserved memory for the
- * next node, this one must extend to the end of the
- * physical node.
- */
- if (limit - end - mem_hole_size(end, limit) < size)
- end = limit;
-
- ret = emu_setup_memblk(ei, pi, nid++ % nr_nodes,
- phys_blk,
- min(end, limit) - start);
- if (ret < 0)
- return ret;
- }
- }
- return 0;
-}
-
-/*
- * Returns the end address of a node so that there is at least `size' amount of
- * non-reserved memory or `max_addr' is reached.
- */
-static u64 __init find_end_of_node(u64 start, u64 max_addr, u64 size)
-{
- u64 end = start + size;
-
- while (end - start - mem_hole_size(start, end) < size) {
- end += FAKE_NODE_MIN_SIZE;
- if (end > max_addr) {
- end = max_addr;
- break;
- }
- }
- return end;
-}
-
-static u64 uniform_size(u64 max_addr, u64 base, u64 hole, int nr_nodes)
-{
- unsigned long max_pfn = PHYS_PFN(max_addr);
- unsigned long base_pfn = PHYS_PFN(base);
- unsigned long hole_pfns = PHYS_PFN(hole);
-
- return PFN_PHYS((max_pfn - base_pfn - hole_pfns) / nr_nodes);
-}
-
-/*
- * Sets up fake nodes of `size' interleaved over physical nodes ranging from
- * `addr' to `max_addr'.
- *
- * Returns zero on success or negative on error.
- */
-static int __init split_nodes_size_interleave_uniform(struct numa_meminfo *ei,
- struct numa_meminfo *pi,
- u64 addr, u64 max_addr, u64 size,
- int nr_nodes, struct numa_memblk *pblk,
- int nid)
-{
- nodemask_t physnode_mask = numa_nodes_parsed;
- int i, ret, uniform = 0;
- u64 min_size;
-
- if ((!size && !nr_nodes) || (nr_nodes && !pblk))
- return -1;
-
- /*
- * In the 'uniform' case split the passed in physical node by
- * nr_nodes, in the non-uniform case, ignore the passed in
- * physical block and try to create nodes of at least size
- * @size.
- *
- * In the uniform case, split the nodes strictly by physical
- * capacity, i.e. ignore holes. In the non-uniform case account
- * for holes and treat @size as a minimum floor.
- */
- if (!nr_nodes)
- nr_nodes = MAX_NUMNODES;
- else {
- nodes_clear(physnode_mask);
- node_set(pblk->nid, physnode_mask);
- uniform = 1;
- }
-
- if (uniform) {
- min_size = uniform_size(max_addr, addr, 0, nr_nodes);
- size = min_size;
- } else {
- /*
- * The limit on emulated nodes is MAX_NUMNODES, so the
- * size per node is increased accordingly if the
- * requested size is too small. This creates a uniform
- * distribution of node sizes across the entire machine
- * (but not necessarily over physical nodes).
- */
- min_size = uniform_size(max_addr, addr,
- mem_hole_size(addr, max_addr), nr_nodes);
- }
- min_size = ALIGN(max(min_size, FAKE_NODE_MIN_SIZE), FAKE_NODE_MIN_SIZE);
- if (size < min_size) {
- pr_err("Fake node size %LuMB too small, increasing to %LuMB\n",
- size >> 20, min_size >> 20);
- size = min_size;
- }
- size = ALIGN_DOWN(size, FAKE_NODE_MIN_SIZE);
-
- /*
- * Fill physical nodes with fake nodes of size until there is no memory
- * left on any of them.
- */
- while (!nodes_empty(physnode_mask)) {
- for_each_node_mask(i, physnode_mask) {
- u64 dma32_end = PFN_PHYS(MAX_DMA32_PFN);
- u64 start, limit, end;
- int phys_blk;
-
- phys_blk = emu_find_memblk_by_nid(i, pi);
- if (phys_blk < 0) {
- node_clear(i, physnode_mask);
- continue;
- }
-
- start = pi->blk[phys_blk].start;
- limit = pi->blk[phys_blk].end;
-
- if (uniform)
- end = start + size;
- else
- end = find_end_of_node(start, limit, size);
- /*
- * If there won't be at least FAKE_NODE_MIN_SIZE of
- * non-reserved memory in ZONE_DMA32 for the next node,
- * this one must extend to the boundary.
- */
- if (end < dma32_end && dma32_end - end -
- mem_hole_size(end, dma32_end) < FAKE_NODE_MIN_SIZE)
- end = dma32_end;
-
- /*
- * If there won't be enough non-reserved memory for the
- * next node, this one must extend to the end of the
- * physical node.
- */
- if ((limit - end - mem_hole_size(end, limit) < size)
- && !uniform)
- end = limit;
-
- ret = emu_setup_memblk(ei, pi, nid++ % MAX_NUMNODES,
- phys_blk,
- min(end, limit) - start);
- if (ret < 0)
- return ret;
- }
- }
- return nid;
-}
-
-static int __init split_nodes_size_interleave(struct numa_meminfo *ei,
- struct numa_meminfo *pi,
- u64 addr, u64 max_addr, u64 size)
-{
- return split_nodes_size_interleave_uniform(ei, pi, addr, max_addr, size,
- 0, NULL, 0);
-}
-
-static int __init setup_emu2phys_nid(int *dfl_phys_nid)
-{
- int i, max_emu_nid = 0;
-
- *dfl_phys_nid = NUMA_NO_NODE;
- for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++) {
- if (emu_nid_to_phys[i] != NUMA_NO_NODE) {
- max_emu_nid = i;
- if (*dfl_phys_nid == NUMA_NO_NODE)
- *dfl_phys_nid = emu_nid_to_phys[i];
- }
- }
-
- return max_emu_nid;
-}
-
-/**
- * numa_emulation - Emulate NUMA nodes
- * @numa_meminfo: NUMA configuration to massage
- * @numa_dist_cnt: The size of the physical NUMA distance table
- *
- * Emulate NUMA nodes according to the numa=fake kernel parameter.
- * @numa_meminfo contains the physical memory configuration and is modified
- * to reflect the emulated configuration on success. @numa_dist_cnt is
- * used to determine the size of the physical distance table.
- *
- * On success, the following modifications are made.
- *
- * - @numa_meminfo is updated to reflect the emulated nodes.
- *
- * - __apicid_to_node[] is updated such that APIC IDs are mapped to the
- * emulated nodes.
- *
- * - NUMA distance table is rebuilt to represent distances between emulated
- * nodes. The distances are determined considering how emulated nodes
- * are mapped to physical nodes and match the actual distances.
- *
- * - emu_nid_to_phys[] reflects how emulated nodes are mapped to physical
- * nodes. This is used by numa_add_cpu() and numa_remove_cpu().
- *
- * If emulation is not enabled or fails, emu_nid_to_phys[] is filled with
- * identity mapping and no other modification is made.
- */
-void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt)
-{
- static struct numa_meminfo ei __initdata;
- static struct numa_meminfo pi __initdata;
- const u64 max_addr = PFN_PHYS(max_pfn);
- u8 *phys_dist = NULL;
- size_t phys_size = numa_dist_cnt * numa_dist_cnt * sizeof(phys_dist[0]);
- int max_emu_nid, dfl_phys_nid;
- int i, j, ret;
-
- if (!emu_cmdline)
- goto no_emu;
-
- memset(&ei, 0, sizeof(ei));
- pi = *numa_meminfo;
-
- for (i = 0; i < MAX_NUMNODES; i++)
- emu_nid_to_phys[i] = NUMA_NO_NODE;
-
- /*
- * If the numa=fake command-line contains a 'M' or 'G', it represents
- * the fixed node size. Otherwise, if it is just a single number N,
- * split the system RAM into N fake nodes.
- */
- if (strchr(emu_cmdline, 'U')) {
- nodemask_t physnode_mask = numa_nodes_parsed;
- unsigned long n;
- int nid = 0;
-
- n = simple_strtoul(emu_cmdline, &emu_cmdline, 0);
- ret = -1;
- for_each_node_mask(i, physnode_mask) {
- /*
- * The reason we pass in blk[0] is due to
- * numa_remove_memblk_from() called by
- * emu_setup_memblk() will delete entry 0
- * and then move everything else up in the pi.blk
- * array. Therefore we should always be looking
- * at blk[0].
- */
- ret = split_nodes_size_interleave_uniform(&ei, &pi,
- pi.blk[0].start, pi.blk[0].end, 0,
- n, &pi.blk[0], nid);
- if (ret < 0)
- break;
- if (ret < n) {
- pr_info("%s: phys: %d only got %d of %ld nodes, failing\n",
- __func__, i, ret, n);
- ret = -1;
- break;
- }
- nid = ret;
- }
- } else if (strchr(emu_cmdline, 'M') || strchr(emu_cmdline, 'G')) {
- u64 size;
-
- size = memparse(emu_cmdline, &emu_cmdline);
- ret = split_nodes_size_interleave(&ei, &pi, 0, max_addr, size);
- } else {
- unsigned long n;
-
- n = simple_strtoul(emu_cmdline, &emu_cmdline, 0);
- ret = split_nodes_interleave(&ei, &pi, 0, max_addr, n);
- }
- if (*emu_cmdline == ':')
- emu_cmdline++;
-
- if (ret < 0)
- goto no_emu;
-
- if (numa_cleanup_meminfo(&ei) < 0) {
- pr_warn("NUMA: Warning: constructed meminfo invalid, disabling emulation\n");
- goto no_emu;
- }
-
- /* copy the physical distance table */
- if (numa_dist_cnt) {
- u64 phys;
-
- phys = memblock_phys_alloc_range(phys_size, PAGE_SIZE, 0,
- PFN_PHYS(max_pfn_mapped));
- if (!phys) {
- pr_warn("NUMA: Warning: can't allocate copy of distance table, disabling emulation\n");
- goto no_emu;
- }
- phys_dist = __va(phys);
-
- for (i = 0; i < numa_dist_cnt; i++)
- for (j = 0; j < numa_dist_cnt; j++)
- phys_dist[i * numa_dist_cnt + j] =
- node_distance(i, j);
- }
-
- /*
- * Determine the max emulated nid and the default phys nid to use
- * for unmapped nodes.
- */
- max_emu_nid = setup_emu2phys_nid(&dfl_phys_nid);
-
- /* commit */
- *numa_meminfo = ei;
-
- /* Make sure numa_nodes_parsed only contains emulated nodes */
- nodes_clear(numa_nodes_parsed);
- for (i = 0; i < ARRAY_SIZE(ei.blk); i++)
- if (ei.blk[i].start != ei.blk[i].end &&
- ei.blk[i].nid != NUMA_NO_NODE)
- node_set(ei.blk[i].nid, numa_nodes_parsed);
-
- /*
- * Transform __apicid_to_node table to use emulated nids by
- * reverse-mapping phys_nid. The maps should always exist but fall
- * back to zero just in case.
- */
- for (i = 0; i < ARRAY_SIZE(__apicid_to_node); i++) {
- if (__apicid_to_node[i] == NUMA_NO_NODE)
- continue;
- for (j = 0; j < ARRAY_SIZE(emu_nid_to_phys); j++)
- if (__apicid_to_node[i] == emu_nid_to_phys[j])
- break;
- __apicid_to_node[i] = j < ARRAY_SIZE(emu_nid_to_phys) ? j : 0;
- }
-
- /* make sure all emulated nodes are mapped to a physical node */
- for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++)
- if (emu_nid_to_phys[i] == NUMA_NO_NODE)
- emu_nid_to_phys[i] = dfl_phys_nid;
-
- /* transform distance table */
- numa_reset_distance();
- for (i = 0; i < max_emu_nid + 1; i++) {
- for (j = 0; j < max_emu_nid + 1; j++) {
- int physi = emu_nid_to_phys[i];
- int physj = emu_nid_to_phys[j];
- int dist;
-
- if (get_option(&emu_cmdline, &dist) == 2)
- ;
- else if (physi >= numa_dist_cnt || physj >= numa_dist_cnt)
- dist = physi == physj ?
- LOCAL_DISTANCE : REMOTE_DISTANCE;
- else
- dist = phys_dist[physi * numa_dist_cnt + physj];
-
- numa_set_distance(i, j, dist);
- }
- }
-
- /* free the copied physical distance table */
- memblock_free(phys_dist, phys_size);
- return;
-
-no_emu:
- /* No emulation. Build identity emu_nid_to_phys[] for numa_add_cpu() */
- for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++)
- emu_nid_to_phys[i] = i;
-}
-
-#ifndef CONFIG_DEBUG_PER_CPU_MAPS
-void numa_add_cpu(int cpu)
-{
- int physnid, nid;
-
- nid = early_cpu_to_node(cpu);
- BUG_ON(nid == NUMA_NO_NODE || !node_online(nid));
-
- physnid = emu_nid_to_phys[nid];
-
- /*
- * Map the cpu to each emulated node that is allocated on the physical
- * node of the cpu's apic id.
- */
- for_each_online_node(nid)
- if (emu_nid_to_phys[nid] == physnid)
- cpumask_set_cpu(cpu, node_to_cpumask_map[nid]);
-}
-
-void numa_remove_cpu(int cpu)
-{
- int i;
-
- for_each_online_node(i)
- cpumask_clear_cpu(cpu, node_to_cpumask_map[i]);
-}
-#else /* !CONFIG_DEBUG_PER_CPU_MAPS */
-static void numa_set_cpumask(int cpu, bool enable)
-{
- int nid, physnid;
-
- nid = early_cpu_to_node(cpu);
- if (nid == NUMA_NO_NODE) {
- /* early_cpu_to_node() already emits a warning and trace */
- return;
- }
-
- physnid = emu_nid_to_phys[nid];
-
- for_each_online_node(nid) {
- if (emu_nid_to_phys[nid] != physnid)
- continue;
-
- debug_cpumask_set_cpu(cpu, nid, enable);
- }
-}
-
-void numa_add_cpu(int cpu)
-{
- numa_set_cpumask(cpu, true);
-}
-
-void numa_remove_cpu(int cpu)
-{
- numa_set_cpumask(cpu, false);
-}
-#endif /* !CONFIG_DEBUG_PER_CPU_MAPS */
diff --git a/drivers/base/arch_numa.c b/drivers/base/arch_numa.c
index 5df0ad5cb09d..67bdbcd0caf9 100644
--- a/drivers/base/arch_numa.c
+++ b/drivers/base/arch_numa.c
@@ -13,6 +13,7 @@
#include <linux/module.h>
#include <linux/of.h>
+#include <asm-generic/numa.h>
#include <asm/sections.h>
struct pglist_data *node_data[MAX_NUMNODES] __read_mostly;
@@ -30,6 +31,8 @@ static __init int numa_parse_early_param(char *opt)
return -EINVAL;
if (str_has_prefix(opt, "off"))
numa_off = true;
+ if (!strncmp(opt, "fake=", 5))
+ return numa_emu_cmdline(opt + 5);
return 0;
}
diff --git a/include/asm-generic/numa.h b/include/asm-generic/numa.h
index 929d7c582a73..4658155a070a 100644
--- a/include/asm-generic/numa.h
+++ b/include/asm-generic/numa.h
@@ -50,12 +50,24 @@ struct numa_meminfo {
struct numa_memblk blk[NR_NODE_MEMBLKS];
};
+#ifdef CONFIG_NUMA_EMU
+#define FAKE_NODE_MIN_SIZE ((u64)32 << 20)
+#define FAKE_NODE_MIN_HASH_MASK (~(FAKE_NODE_MIN_SIZE - 1UL))
+
extern struct numa_meminfo numa_meminfo;
+extern char *emu_cmdline __initdata;
+int numa_emu_cmdline(char *str);
int __init numa_register_memblks(struct numa_meminfo *mi);
int __init numa_cleanup_meminfo(struct numa_meminfo *mi);
void __init numa_emulation(struct numa_meminfo *numa_meminfo,
int numa_dist_cnt);
+#else
+static inline int numa_emu_cmdline(char *str)
+{
+ return -EINVAL;
+}
+#endif
#else /* CONFIG_NUMA */
diff --git a/mm/Kconfig b/mm/Kconfig
index 264a2df5ecf5..22bead675ee6 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -549,6 +549,14 @@ config ARCH_ENABLE_MEMORY_HOTPLUG
config ARCH_ENABLE_MEMORY_HOTREMOVE
bool
+config NUMA_EMU
+ bool "NUMA emulation (EXPERIMENTAL)"
+ depends on NUMA && (X86 || ARM64)
+ help
+ Enable NUMA emulation. A flat machine will be split
+ into virtual nodes when booted with "numa=fake=N", where N is the
+ number of nodes. This is only useful for debugging.
+
# eventually, we can have this option just 'select SPARSEMEM'
menuconfig MEMORY_HOTPLUG
bool "Memory hotplug"
diff --git a/mm/numa.c b/mm/numa.c
index 88277e8404f0..3cc01f06a2a6 100644
--- a/mm/numa.c
+++ b/mm/numa.c
@@ -16,6 +16,10 @@
struct numa_meminfo numa_meminfo __initdata_or_meminfo;
struct numa_meminfo numa_reserved_meminfo __initdata_or_meminfo;
+#ifdef CONFIG_NUMA_EMU
+char *emu_cmdline __initdata;
+#endif
+
/*
* Set nodes, which have memory in @mi, in *@...emask.
*/
@@ -296,3 +300,11 @@ int __weak __init numa_register_memblks(struct numa_meminfo *mi)
return 0;
}
+
+#ifdef CONFIG_NUMA_EMU
+int __init numa_emu_cmdline(char *str)
+{
+ emu_cmdline = str;
+ return 0;
+}
+#endif
--
2.32.0.3.gf3a3e56d6
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