> From: Dave Martin [mailto:dave.martin@xxxxxxxxxx] > Sent: Thursday, June 28, 2012 1:02 AM > > For me, it appears that this block just contains the initial region passed > in ATAG_MEM or on the command line, with some reservations for > swapper_pg_dir, the kernel text/data, device tree and initramfs. > > So far as I can tell, the only memory guaranteed to be mapped here is the > kernel image: there may be no guarantee that there is any unused space in > this region which could be used to allocate extra page tables. > The rest appears during the execution of map_lowmem(). > > Cheers > ---Dave Thank you for your comment, Dave! It was not that sophisticated choice, but I thought that normal embedded system trying to reduce the BOM would have a big-enough first memblock memory region. However you're right. There can be exceptional systems. Then, how do you think about following manner: diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c index e5dad60..0bc5316 100644 --- a/arch/arm/mm/mmu.c +++ b/arch/arm/mm/mmu.c @@ -1094,6 +1094,16 @@ static void __init kmap_init(void) static void __init map_lowmem(void) { struct memblock_region *reg; + phys_addr_t pmd_map_end = 0; + + for_each_memblock(memory, reg) { + pmd_map_end = reg->base + reg->size; + if((reg->base | reg->size) & ~PMD_MASK) + break; + } + if(pmd_map_end > lowmem_limit) + pmd_map_end = lowmem_limit; + memblock_set_current_limit(pmd_map_end & PMD_MASK); /* Map all the lowmem memory banks. */ for_each_memblock(memory, reg) { @@ -1113,6 +1123,8 @@ static void __init map_lowmem(void) create_mapping(&map); } + + memblock_set_current_limit(lowmem_limit); } /* @@ -1123,8 +1135,6 @@ void __init paging_init(struct machine_desc *mdesc) { void *zero_page; - memblock_set_current_limit(arm_lowmem_limit); - build_mem_type_table(); prepare_page_table(); map_lowmem(); This will not limit the PTE-allocation to near the end of first bank. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>