highmem and VMALLOC_END

Chao Xie cxie4 at marvell.com
Tue Nov 23 04:42:24 EST 2010


hi
in arch/arm/mmu,c, when define CONFIG_HIGHMEM, in sanity_check_meminfo, it will check the memory banks, 
and if the memory bank is in high memory, it will be marked as highmem.
	lowmem_limit = __pa(vmalloc_min - 1) + 1;
	memblock_set_current_limit(lowmem_limit);

	for (i = 0, j = 0; i < meminfo.nr_banks; i++) {
		struct membank *bank = &meminfo.bank[j];
		*bank = meminfo.bank[i];

#ifdef CONFIG_HIGHMEM
		if (__va(bank->start) > vmalloc_min ||
			__va(bank->start) < (void *)PAGE_OFFSET)
				highmem = 1;
if VMALLOC_END is 0xe8000000, and "vmalloc" is 0x18000000, vmalloc_min will be 0xd0000000.
There are two banks, each bank is 256MB. Based on __phys_to_virt(), __va(first bank start) is 
0xc0000000, while __va(second bank start) is 0xd0000000. Based on previous if, the second bank 
is not marked highmem, but in fact it will occupy the virtual address from 0xd0000000 to 0xdfffffff,
and it should be in high memory.
It will be fine if change the code as
--		if (__va(bank->start) > vmalloc_min ||
++		if (__va(bank->start) >= vmalloc_min ||
Is it a bug or I understand wrong? Thanks.




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