ARM: add helpful message when truncating physical memory

Add a nmessage to suggest that HIGHMEM is enabled when physical memory
is truncated due to lack of virtual address space to map it in the low
memory mapping.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 6 insertions, 0 deletions

diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 904d1532e6d0..79de062c6077 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -1072,6 +1072,7 @@ void __init sanity_check_meminfo(void)
         int highmem = 0;
         phys_addr_t vmalloc_limit = __pa(vmalloc_min - 1) + 1;
         struct memblock_region *reg;
+        bool should_use_highmem = false;
 
         for_each_memblock(memory, reg) {
                 phys_addr_t block_start = reg->base;
@@ -1090,6 +1091,7 @@ void __init sanity_check_meminfo(void)
                                 pr_notice("Ignoring RAM at %pa-%pa (!CONFIG_HIGHMEM)\n",
                                           &block_start, &block_end);
                                 memblock_remove(reg->base, reg->size);
+                                should_use_highmem = true;
                                 continue;
                         }
 
@@ -1100,6 +1102,7 @@ void __init sanity_check_meminfo(void)
                                           &block_start, &block_end, &vmalloc_limit);
                                 memblock_remove(vmalloc_limit, overlap_size);
                                 block_end = vmalloc_limit;
+                                should_use_highmem = true;
                         }
                 }
 
@@ -1134,6 +1137,9 @@ void __init sanity_check_meminfo(void)
                 }
         }
 
+        if (should_use_highmem)
+                pr_notice("Consider using a HIGHMEM enabled kernel.\n");
+
         high_memory = __va(arm_lowmem_limit - 1) + 1;
 
         /*