x86, 32-bit: clean up find_low_pfn_range()

Impact: cleanup

Split find_low_pfn_range() into two functions:

 - lowmem_pfn_init()
 - highmem_pfn_init()

The former gets called if all of RAM fits into lowmem,
otherwise we call highmem_pfn_init().

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 79 insertions, 58 deletions

diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index e77459dd38ae..9d36eb9ebd53 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -675,75 +675,96 @@ static int __init parse_highmem(char *arg)
 }
 early_param("highmem", parse_highmem);
 
+#define MSG_HIGHMEM_TOO_BIG \
+        "highmem size (%luMB) is bigger than pages available (%luMB)!\n"
+
+#define MSG_LOWMEM_TOO_SMALL \
+        "highmem size (%luMB) results in <64MB lowmem, ignoring it!\n"
 /*
- * Determine low and high memory ranges:
+ * All of RAM fits into lowmem - but if user wants highmem
+ * artificially via the highmem=x boot parameter then create
+ * it:
  */
-void __init find_low_pfn_range(void)
+void __init lowmem_pfn_init(void)
 {
-        /* it could update max_pfn */
-
-        /* max_low_pfn is 0, we already have early_res support */
-
-        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 %luMB.\n",
-                                pages_to_mb(max_pfn - MAXMEM_PFN),
+        if (highmem_pages == -1)
+                highmem_pages = 0;
+#ifdef CONFIG_HIGHMEM
+        if (highmem_pages >= max_pfn) {
+                printk(KERN_ERR MSG_HIGHMEM_TOO_BIG,
+                        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 MSG_LOWMEM_TOO_SMALL,
                                 pages_to_mb(highmem_pages));
                         highmem_pages = 0;
                 }
-                max_low_pfn = MAXMEM_PFN;
+                max_low_pfn -= highmem_pages;
+        }
+#else
+        if (highmem_pages)
+                printk(KERN_ERR "ignoring highmem size on non-highmem kernel!\n");
+#endif
+}
+
+#define MSG_HIGHMEM_TOO_SMALL \
+        "only %luMB highmem pages available, ignoring highmem size of %luMB!\n"
+
+#define MSG_HIGHMEM_TRIMMED \
+        "Warning: only 4GB will be used. Use a HIGHMEM64G enabled kernel!\n"
+/*
+ * We have more RAM than fits into lowmem - we try to put it into
+ * highmem, also taking the highmem=x boot parameter into account:
+ */
+void __init highmem_pfn_init(void)
+{
+        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 MSG_HIGHMEM_TOO_SMALL,
+                        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;
+        /* 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");
-                }
+        if (max_pfn > MAX_NONPAE_PFN) {
+                max_pfn = MAX_NONPAE_PFN;
+                printk(KERN_WARNING MSG_HIGHMEM_TRIMMED);
+        }
 #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 (%luMB) 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 %luMB 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
-        }
+}
+
+/*
+ * Determine low and high memory ranges:
+ */
+void __init find_low_pfn_range(void)
+{
+        /* it could update max_pfn */
+
+        /* max_low_pfn is 0, we already have early_res support */
+        max_low_pfn = max_pfn;
+
+        if (max_low_pfn > MAXMEM_PFN)
+                highmem_pfn_init();
+        else
+                lowmem_pfn_init();
 }
 
 #ifndef CONFIG_NEED_MULTIPLE_NODES