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Subject[PATCH] ppc64: Add mem=X boot command line option
Date
Hi Andrew,

This patch adds the mem=X boot command line option for PPC64.

On iSeries the user's mem=X value is aligned to PAGE_SIZE, on
pSeries we align to 16 MB which is the size of a large page.

The iSeries implementation is fairly straight forward, we declare mem=X
as an early_param() and then in iSeries_init_early() we modify the
systemcfg->physicalMemorySize based on that value.

On pSeries the mem=X option is parsed in prom_init.c before the kernel proper
starts, and is used to modify prom_init_mem()'s idea of memory. The mem=X
value and computed tce_alloc_start/end values are saved by prom_init() into
the device tree for later use by the kernel.

The device tree properties are read by the kernel in early_dt_scan_chosen(),
and used to modify the lmb structure in early_init_devtree(). That's the guts
of it.

On non-LPAR machines the tce_alloc_start/end values are read from the device
tree and used in htab_initialize() to make sure the TCE table is mapped at
the real top of RAM.

If NUMA is enabled we also have to make changes in parse_numa_properties()
and do_init_bootmem() to exclude memory regions above the memory limit,
and truncate any region which stradles the limit.

NB. This patch does not facilitate using mem=X to give drivers access to
large regions of contiguous memory.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
---

This is almost identical to the patch I posted last week, with one minor
change to make boot messages look the same on iSeries & pSeries, and
a few little white space and comment tweaks.

It has been tested on iSeries, pSeries, pSeries LPAR, G5 and Maple.

Thanks to BenH, Anton, Olof, Stephen, Mike & Maneesh for their help.

cheers!

arch/ppc64/kernel/iSeries_setup.c | 40 +++++++----
arch/ppc64/kernel/lmb.c | 26 +++++++
arch/ppc64/kernel/prom.c | 15 ++++
arch/ppc64/kernel/prom_init.c | 137 +++++++++++++++++++++++++++++++++++---
arch/ppc64/kernel/setup.c | 20 ++++-
arch/ppc64/mm/hash_utils.c | 23 +++++-
arch/ppc64/mm/numa.c | 46 +++++++++++-
include/asm-ppc64/lmb.h | 1
8 files changed, 276 insertions(+), 32 deletions(-)

Index: bk-current/arch/ppc64/kernel/setup.c
===================================================================
--- bk-current.orig/arch/ppc64/kernel/setup.c
+++ bk-current/arch/ppc64/kernel/setup.c
@@ -636,12 +636,11 @@ void __init setup_system(void)
early_console_initialized = 1;
register_console(&udbg_console);

-#endif /* !CONFIG_PPC_ISERIES */
-
/* Save unparsed command line copy for /proc/cmdline */
strlcpy(saved_command_line, cmd_line, COMMAND_LINE_SIZE);

parse_early_param();
+#endif /* !CONFIG_PPC_ISERIES */

#if defined(CONFIG_SMP) && !defined(CONFIG_PPC_ISERIES)
/*
@@ -800,20 +799,31 @@ struct seq_operations cpuinfo_op = {
.show = show_cpuinfo,
};

-#if 0 /* XXX not currently used */
+/*
+ * These three variables are used to save values passed to us by prom_init()
+ * via the device tree. The TCE variables are needed because with a memory_limit
+ * in force we may need to explicitly map the TCE are at the top of RAM.
+ */
unsigned long memory_limit;
+unsigned long tce_alloc_start;
+unsigned long tce_alloc_end;

+#ifdef CONFIG_PPC_ISERIES
+/*
+ * On iSeries we just parse the mem=X option from the command line.
+ * On pSeries it's a bit more complicated, see prom_init_mem()
+ */
static int __init early_parsemem(char *p)
{
if (!p)
return 0;

- memory_limit = memparse(p, &p);
+ memory_limit = ALIGN(memparse(p, &p), PAGE_SIZE);

return 0;
}
early_param("mem", early_parsemem);
-#endif
+#endif /* CONFIG_PPC_ISERIES */

#ifdef CONFIG_PPC_MULTIPLATFORM
static int __init set_preferred_console(void)
Index: bk-current/arch/ppc64/kernel/lmb.c
===================================================================
--- bk-current.orig/arch/ppc64/kernel/lmb.c
+++ bk-current/arch/ppc64/kernel/lmb.c
@@ -344,3 +344,29 @@ lmb_abs_to_phys(unsigned long aa)

return pa;
}
+
+/*
+ * Truncate the lmb list to memory_limit if it's set
+ * You must call lmb_analyze() after this.
+ */
+void __init lmb_enforce_memory_limit(void)
+{
+ extern unsigned long memory_limit;
+ unsigned long i, limit;
+ struct lmb_region *mem = &(lmb.memory);
+
+ if (! memory_limit)
+ return;
+
+ limit = memory_limit;
+ for (i = 0; i < mem->cnt; i++) {
+ if (limit > mem->region[i].size) {
+ limit -= mem->region[i].size;
+ continue;
+ }
+
+ mem->region[i].size = limit;
+ mem->cnt = i + 1;
+ break;
+ }
+}
Index: bk-current/include/asm-ppc64/lmb.h
===================================================================
--- bk-current.orig/include/asm-ppc64/lmb.h
+++ bk-current/include/asm-ppc64/lmb.h
@@ -51,6 +51,7 @@ extern unsigned long __init lmb_alloc_ba
extern unsigned long __init lmb_phys_mem_size(void);
extern unsigned long __init lmb_end_of_DRAM(void);
extern unsigned long __init lmb_abs_to_phys(unsigned long);
+extern void __init lmb_enforce_memory_limit(void);

extern void lmb_dump_all(void);

Index: bk-current/arch/ppc64/kernel/iSeries_setup.c
===================================================================
--- bk-current.orig/arch/ppc64/kernel/iSeries_setup.c
+++ bk-current/arch/ppc64/kernel/iSeries_setup.c
@@ -285,7 +285,7 @@ static unsigned long iSeries_process_mai
return mem_blocks;
}

-static void __init iSeries_parse_cmdline(void)
+static void __init iSeries_get_cmdline(void)
{
char *p, *q;

@@ -305,6 +305,8 @@ static void __init iSeries_parse_cmdline

static void __init iSeries_init_early(void)
{
+ extern unsigned long memory_limit;
+
DBG(" -> iSeries_init_early()\n");

ppcdbg_initialize();
@@ -352,6 +354,31 @@ static void __init iSeries_init_early(vo
*/
build_iSeries_Memory_Map();

+ iSeries_get_cmdline();
+
+ /* Save unparsed command line copy for /proc/cmdline */
+ strlcpy(saved_command_line, cmd_line, COMMAND_LINE_SIZE);
+
+ /* Parse early parameters, in particular mem=x */
+ parse_early_param();
+
+ if (memory_limit) {
+ if (memory_limit < systemcfg->physicalMemorySize)
+ systemcfg->physicalMemorySize = memory_limit;
+ else {
+ printk("Ignoring mem=%lu >= ram_top.\n", memory_limit);
+ memory_limit = 0;
+ }
+ }
+
+ /* Bolt kernel mappings for all of memory (or just a bit if we've got a limit) */
+ iSeries_bolt_kernel(0, systemcfg->physicalMemorySize);
+
+ lmb_init();
+ lmb_add(0, systemcfg->physicalMemorySize);
+ lmb_analyze();
+ lmb_reserve(0, __pa(klimit));
+
/* Initialize machine-dependency vectors */
#ifdef CONFIG_SMP
smp_init_iSeries();
@@ -377,9 +404,6 @@ static void __init iSeries_init_early(vo
initrd_start = initrd_end = 0;
#endif /* CONFIG_BLK_DEV_INITRD */

-
- iSeries_parse_cmdline();
-
DBG(" <- iSeries_init_early()\n");
}

@@ -540,14 +564,6 @@ static void __init build_iSeries_Memory_
* nextPhysChunk
*/
systemcfg->physicalMemorySize = chunk_to_addr(nextPhysChunk);
-
- /* Bolt kernel mappings for all of memory */
- iSeries_bolt_kernel(0, systemcfg->physicalMemorySize);
-
- lmb_init();
- lmb_add(0, systemcfg->physicalMemorySize);
- lmb_analyze(); /* ?? */
- lmb_reserve(0, __pa(klimit));
}

/*
Index: bk-current/arch/ppc64/kernel/prom.c
===================================================================
--- bk-current.orig/arch/ppc64/kernel/prom.c
+++ bk-current/arch/ppc64/kernel/prom.c
@@ -912,6 +912,8 @@ static int __init early_init_dt_scan_cho
const char *full_path, void *data)
{
u32 *prop;
+ u64 *prop64;
+ extern unsigned long memory_limit, tce_alloc_start, tce_alloc_end;

if (strcmp(full_path, "/chosen") != 0)
return 0;
@@ -928,6 +930,18 @@ static int __init early_init_dt_scan_cho
if (get_flat_dt_prop(node, "linux,iommu-force-on", NULL) != NULL)
iommu_force_on = 1;

+ prop64 = (u64*)get_flat_dt_prop(node, "linux,memory-limit", NULL);
+ if (prop64)
+ memory_limit = *prop64;
+
+ prop64 = (u64*)get_flat_dt_prop(node, "linux,tce-alloc-start", NULL);
+ if (prop64)
+ tce_alloc_start = *prop64;
+
+ prop64 = (u64*)get_flat_dt_prop(node, "linux,tce-alloc-end", NULL);
+ if (prop64)
+ tce_alloc_end = *prop64;
+
#ifdef CONFIG_PPC_RTAS
/* To help early debugging via the front panel, we retreive a minimal
* set of RTAS infos now if available
@@ -1067,6 +1081,7 @@ void __init early_init_devtree(void *par
lmb_init();
scan_flat_dt(early_init_dt_scan_root, NULL);
scan_flat_dt(early_init_dt_scan_memory, NULL);
+ lmb_enforce_memory_limit();
lmb_analyze();
systemcfg->physicalMemorySize = lmb_phys_mem_size();
lmb_reserve(0, __pa(klimit));
Index: bk-current/arch/ppc64/mm/hash_utils.c
===================================================================
--- bk-current.orig/arch/ppc64/mm/hash_utils.c
+++ bk-current/arch/ppc64/mm/hash_utils.c
@@ -149,6 +149,8 @@ void __init htab_initialize(void)
unsigned long pteg_count;
unsigned long mode_rw;
int i, use_largepages = 0;
+ unsigned long base = 0, size = 0;
+ extern unsigned long tce_alloc_start, tce_alloc_end;

DBG(" -> htab_initialize()\n");

@@ -204,8 +206,6 @@ void __init htab_initialize(void)

/* create bolted the linear mapping in the hash table */
for (i=0; i < lmb.memory.cnt; i++) {
- unsigned long base, size;
-
base = lmb.memory.region[i].physbase + KERNELBASE;
size = lmb.memory.region[i].size;

@@ -234,6 +234,25 @@ void __init htab_initialize(void)
#endif /* CONFIG_U3_DART */
create_pte_mapping(base, base + size, mode_rw, use_largepages);
}
+
+ /*
+ * If we have a memory_limit and we've allocated TCEs then we need to
+ * explicitly map the TCE area at the top of RAM. We also cope with the
+ * case that the TCEs start below memory_limit.
+ * tce_alloc_start/end are 16MB aligned so the mapping should work
+ * for either 4K or 16MB pages.
+ */
+ if (tce_alloc_start) {
+ tce_alloc_start += KERNELBASE;
+ tce_alloc_end += KERNELBASE;
+
+ if (base + size >= tce_alloc_start)
+ tce_alloc_start = base + size + 1;
+
+ create_pte_mapping(tce_alloc_start, tce_alloc_end,
+ mode_rw, use_largepages);
+ }
+
DBG(" <- htab_initialize()\n");
}
#undef KB
Index: bk-current/arch/ppc64/mm/numa.c
===================================================================
--- bk-current.orig/arch/ppc64/mm/numa.c
+++ bk-current/arch/ppc64/mm/numa.c
@@ -285,6 +285,35 @@ static int cpu_numa_callback(struct noti
return ret;
}

+/*
+ * Check and possibly modify a memory region to enforce the memory limit.
+ *
+ * Returns the size the region should have to enforce the memory limit.
+ * This will either be the original value of size, a truncated value,
+ * or zero. If the returned value of size is 0 the region should be
+ * discarded as it lies wholy above the memory limit.
+ */
+static unsigned long __init numa_enforce_memory_limit(unsigned long start, unsigned long size)
+{
+ /*
+ * We use lmb_end_of_DRAM() in here instead of memory_limit because
+ * we've already adjusted it for the limit and it takes care of
+ * having memory holes below the limit.
+ */
+ extern unsigned long memory_limit;
+
+ if (! memory_limit)
+ return size;
+
+ if (start + size <= lmb_end_of_DRAM())
+ return size;
+
+ if (start >= lmb_end_of_DRAM())
+ return 0;
+
+ return lmb_end_of_DRAM() - start;
+}
+
static int __init parse_numa_properties(void)
{
struct device_node *cpu = NULL;
@@ -373,6 +402,13 @@ new_range:
if (max_domain < numa_domain)
max_domain = numa_domain;

+ if (! (size = numa_enforce_memory_limit(start, size))) {
+ if (--ranges)
+ goto new_range;
+ else
+ continue;
+ }
+
/*
* Initialize new node struct, or add to an existing one.
*/
@@ -405,8 +441,7 @@ new_range:
numa_memory_lookup_table[i >> MEMORY_INCREMENT_SHIFT] =
numa_domain;

- ranges--;
- if (ranges)
+ if (--ranges)
goto new_range;
}

@@ -614,8 +649,11 @@ new_range:
if (numa_domain != nid)
continue;

- dbg("free_bootmem %lx %lx\n", mem_start, mem_size);
- free_bootmem_node(NODE_DATA(nid), mem_start, mem_size);
+ mem_size = numa_enforce_memory_limit(mem_start, mem_size);
+ if (mem_size) {
+ dbg("free_bootmem %lx %lx\n", mem_start, mem_size);
+ free_bootmem_node(NODE_DATA(nid), mem_start, mem_size);
+ }

if (--ranges) /* process all ranges in cell */
goto new_range;
Index: bk-current/arch/ppc64/kernel/prom_init.c
===================================================================
--- bk-current.orig/arch/ppc64/kernel/prom_init.c
+++ bk-current/arch/ppc64/kernel/prom_init.c
@@ -177,6 +177,10 @@ static int __initdata of_platform;

static char __initdata prom_cmd_line[COMMAND_LINE_SIZE];

+static unsigned long __initdata prom_memory_limit;
+static unsigned long __initdata prom_tce_alloc_start;
+static unsigned long __initdata prom_tce_alloc_end;
+
static unsigned long __initdata alloc_top;
static unsigned long __initdata alloc_top_high;
static unsigned long __initdata alloc_bottom;
@@ -384,10 +388,70 @@ static int __init prom_setprop(phandle n
(u32)(unsigned long) value, (u32) valuelen);
}

+/* We can't use the standard versions because of RELOC headaches. */
+#define isxdigit(c) (('0' <= (c) && (c) <= '9') \
+ || ('a' <= (c) && (c) <= 'f') \
+ || ('A' <= (c) && (c) <= 'F'))
+
+#define isdigit(c) ('0' <= (c) && (c) <= '9')
+#define islower(c) ('a' <= (c) && (c) <= 'z')
+#define toupper(c) (islower(c) ? ((c) - 'a' + 'A') : (c))
+
+unsigned long prom_strtoul(const char *cp, const char **endp)
+{
+ unsigned long result = 0, base = 10, value;
+
+ if (*cp == '0') {
+ base = 8;
+ cp++;
+ if (toupper(*cp) == 'X') {
+ cp++;
+ base = 16;
+ }
+ }
+
+ while (isxdigit(*cp) &&
+ (value = isdigit(*cp) ? *cp - '0' : toupper(*cp) - 'A' + 10) < base) {
+ result = result * base + value;
+ cp++;
+ }
+
+ if (endp)
+ *endp = cp;
+
+ return result;
+}
+
+unsigned long prom_memparse(const char *ptr, const char **retptr)
+{
+ unsigned long ret = prom_strtoul(ptr, retptr);
+ int shift = 0;
+
+ /*
+ * We can't use a switch here because GCC *may* generate a
+ * jump table which won't work, because we're not running at
+ * the address we're linked at.
+ */
+ if ('G' == **retptr || 'g' == **retptr)
+ shift = 30;
+
+ if ('M' == **retptr || 'm' == **retptr)
+ shift = 20;
+
+ if ('K' == **retptr || 'k' == **retptr)
+ shift = 10;
+
+ if (shift) {
+ ret <<= shift;
+ (*retptr)++;
+ }
+
+ return ret;
+}

/*
* Early parsing of the command line passed to the kernel, used for
- * the options that affect the iommu
+ * "mem=x" and the options that affect the iommu
*/
static void __init early_cmdline_parse(void)
{
@@ -418,6 +482,14 @@ static void __init early_cmdline_parse(v
else if (!strncmp(opt, RELOC("force"), 5))
RELOC(iommu_force_on) = 1;
}
+
+ opt = strstr(RELOC(prom_cmd_line), RELOC("mem="));
+ if (opt) {
+ opt += 4;
+ RELOC(prom_memory_limit) = prom_memparse(opt, (const char **)&opt);
+ /* Align to 16 MB == size of large page */
+ RELOC(prom_memory_limit) = ALIGN(RELOC(prom_memory_limit), 0x1000000);
+ }
}

/*
@@ -664,15 +736,7 @@ static void __init prom_init_mem(void)
}
}

- /* Setup our top/bottom alloc points, that is top of RMO or top of
- * segment 0 when running non-LPAR
- */
- if ( RELOC(of_platform) == PLATFORM_PSERIES_LPAR )
- RELOC(alloc_top) = RELOC(rmo_top);
- else
- RELOC(alloc_top) = RELOC(rmo_top) = min(0x40000000ul, RELOC(ram_top));
RELOC(alloc_bottom) = PAGE_ALIGN(RELOC(klimit) - offset + 0x4000);
- RELOC(alloc_top_high) = RELOC(ram_top);

/* Check if we have an initrd after the kernel, if we do move our bottom
* point to after it
@@ -681,8 +745,41 @@ static void __init prom_init_mem(void)
if (RELOC(prom_initrd_end) > RELOC(alloc_bottom))
RELOC(alloc_bottom) = PAGE_ALIGN(RELOC(prom_initrd_end));
}
+
+ /*
+ * If prom_memory_limit is set we reduce the upper limits *except* for
+ * alloc_top_high. This must be the real top of RAM so we can put
+ * TCE's up there.
+ */
+
+ RELOC(alloc_top_high) = RELOC(ram_top);
+
+ if (RELOC(prom_memory_limit)) {
+ if (RELOC(prom_memory_limit) <= RELOC(alloc_bottom)) {
+ prom_printf("Ignoring mem=%x <= alloc_bottom.\n",
+ RELOC(prom_memory_limit));
+ RELOC(prom_memory_limit) = 0;
+ } else if (RELOC(prom_memory_limit) >= RELOC(ram_top)) {
+ prom_printf("Ignoring mem=%x >= ram_top.\n",
+ RELOC(prom_memory_limit));
+ RELOC(prom_memory_limit) = 0;
+ } else {
+ RELOC(ram_top) = RELOC(prom_memory_limit);
+ RELOC(rmo_top) = min(RELOC(rmo_top), RELOC(prom_memory_limit));
+ }
+ }
+
+ /*
+ * Setup our top alloc point, that is top of RMO or top of
+ * segment 0 when running non-LPAR.
+ */
+ if ( RELOC(of_platform) == PLATFORM_PSERIES_LPAR )
+ RELOC(alloc_top) = RELOC(rmo_top);
+ else
+ RELOC(alloc_top) = RELOC(rmo_top) = min(0x40000000ul, RELOC(ram_top));

prom_printf("memory layout at init:\n");
+ prom_printf(" memory_limit : %x (16 MB aligned)\n", RELOC(prom_memory_limit));
prom_printf(" alloc_bottom : %x\n", RELOC(alloc_bottom));
prom_printf(" alloc_top : %x\n", RELOC(alloc_top));
prom_printf(" alloc_top_hi : %x\n", RELOC(alloc_top_high));
@@ -871,6 +968,16 @@ static void __init prom_initialize_tce_t

reserve_mem(local_alloc_bottom, local_alloc_top - local_alloc_bottom);

+ if (RELOC(prom_memory_limit)) {
+ /*
+ * We align the start to a 16MB boundary so we can map the TCE area
+ * using large pages if possible. The end should be the top of RAM
+ * so no need to align it.
+ */
+ RELOC(prom_tce_alloc_start) = _ALIGN_DOWN(local_alloc_bottom, 0x1000000);
+ RELOC(prom_tce_alloc_end) = local_alloc_top;
+ }
+
/* Flag the first invalid entry */
prom_debug("ending prom_initialize_tce_table\n");
}
@@ -1684,9 +1791,21 @@ unsigned long __init prom_init(unsigned
*/
if (RELOC(ppc64_iommu_off))
prom_setprop(_prom->chosen, "linux,iommu-off", NULL, 0);
+
if (RELOC(iommu_force_on))
prom_setprop(_prom->chosen, "linux,iommu-force-on", NULL, 0);

+ if (RELOC(prom_memory_limit))
+ prom_setprop(_prom->chosen, "linux,memory-limit",
+ PTRRELOC(&prom_memory_limit), sizeof(RELOC(prom_memory_limit)));
+
+ if (RELOC(prom_tce_alloc_start)) {
+ prom_setprop(_prom->chosen, "linux,tce-alloc-start",
+ PTRRELOC(&prom_tce_alloc_start), sizeof(RELOC(prom_tce_alloc_start)));
+ prom_setprop(_prom->chosen, "linux,tce-alloc-end",
+ PTRRELOC(&prom_tce_alloc_end), sizeof(RELOC(prom_tce_alloc_end)));
+ }
+
/*
* Now finally create the flattened device-tree
*/
-
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