x86: move find_max_low_pfn to init_32.c

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 88 insertions, 1 deletions

diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 98080782ee47..d1017336f1b5 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -540,8 +540,95 @@ static void __init set_nx(void)
 }
 #endif
 
+/* user-defined highmem size */
+static unsigned int highmem_pages = -1;
+
+/*
+ * highmem=size forces highmem to be exactly 'size' bytes.
+ * This works even on boxes that have no highmem otherwise.
+ * This also works to reduce highmem size on bigger boxes.
+ */
+static int __init parse_highmem(char *arg)
+{
+        if (!arg)
+                return -EINVAL;
+
+        highmem_pages = memparse(arg, &arg) >> PAGE_SHIFT;
+        return 0;
+}
+early_param("highmem", parse_highmem);
+
+/*
+ * Determine low and high memory ranges:
+ */
+unsigned long __init find_max_low_pfn(void)
+{
+        unsigned long max_low_pfn;
+
+        max_low_pfn = max_pfn;
+        if (max_low_pfn > MAXMEM_PFN) {
+                if (highmem_pages == -1)
+                        highmem_pages = max_pfn - MAXMEM_PFN;
+                if (highmem_pages + MAXMEM_PFN < max_pfn)
+                        max_pfn = MAXMEM_PFN + highmem_pages;
+                if (highmem_pages + MAXMEM_PFN > max_pfn) {
+                        printk(KERN_WARNING "only %luMB highmem pages "
+                                "available, ignoring highmem size of %uMB.\n",
+                                pages_to_mb(max_pfn - MAXMEM_PFN),
+                                pages_to_mb(highmem_pages));
+                        highmem_pages = 0;
+                }
+                max_low_pfn = MAXMEM_PFN;
+#ifndef CONFIG_HIGHMEM
+                /* Maximum memory usable is what is directly addressable */
+                printk(KERN_WARNING "Warning only %ldMB will be used.\n",
+                                        MAXMEM>>20);
+                if (max_pfn > MAX_NONPAE_PFN)
+                        printk(KERN_WARNING
+                                 "Use a HIGHMEM64G enabled kernel.\n");
+                else
+                        printk(KERN_WARNING "Use a HIGHMEM enabled kernel.\n");
+                max_pfn = MAXMEM_PFN;
+#else /* !CONFIG_HIGHMEM */
+#ifndef CONFIG_HIGHMEM64G
+                if (max_pfn > MAX_NONPAE_PFN) {
+                        max_pfn = MAX_NONPAE_PFN;
+                        printk(KERN_WARNING "Warning only 4GB will be used."
+                                "Use a HIGHMEM64G enabled kernel.\n");
+                }
+#endif /* !CONFIG_HIGHMEM64G */
+#endif /* !CONFIG_HIGHMEM */
+        } else {
+                if (highmem_pages == -1)
+                        highmem_pages = 0;
+#ifdef CONFIG_HIGHMEM
+                if (highmem_pages >= max_pfn) {
+                        printk(KERN_ERR "highmem size specified (%uMB) is "
+                                "bigger than pages available (%luMB)!.\n",
+                                pages_to_mb(highmem_pages),
+                                pages_to_mb(max_pfn));
+                        highmem_pages = 0;
+                }
+                if (highmem_pages) {
+                        if (max_low_pfn - highmem_pages <
+                            64*1024*1024/PAGE_SIZE){
+                                printk(KERN_ERR "highmem size %uMB results in "
+                                "smaller than 64MB lowmem, ignoring it.\n"
+                                        , pages_to_mb(highmem_pages));
+                                highmem_pages = 0;
+                        }
+                        max_low_pfn -= highmem_pages;
+                }
+#else
+                if (highmem_pages)
+                        printk(KERN_ERR "ignoring highmem size on non-highmem"
+                                        " kernel!\n");
+#endif
+        }
+        return max_low_pfn;
+}
+
 #ifndef CONFIG_NEED_MULTIPLE_NODES
-extern unsigned long find_max_low_pfn(void);
 unsigned long __init initmem_init(unsigned long start_pfn,
                                   unsigned long end_pfn)
 {