簡介：介紹一下上文遺留的兩個結構memblock以及meminfo.
相關閱讀：http://www.linuxidc.com/Linux/2012-02/53139.htm
**********************************
* 在arch/arm/kernel/setup.c中，
* sanity_check_meminfo();
**********************************
arm_memblock_init(&meminfo, mdesc);
arch/arm/mm中，
void __init sanity_check_meminfo(void)
{
int i, j, highmem = 0;
//遍歷所有的bank
for (i = 0, j = 0; i < meminfo.nr_banks; i++) {
struct membank *bank = &meminfo.bank[j];
*bank = meminfo.bank[i];
#ifdef CONFIG_HIGHMEM
//如果定義了高端內存，地址范圍在高端內，則標記
if (__va(bank->start) >= vmalloc_min ||
__va(bank->start) < (void *)PAGE_OFFSET)
highmem = 1;
bank->highmem = highmem; //標記
/*
* Split those memory banks which are partially overlapping
* the vmalloc area greatly simplifying things later.
*/
//范圍在低端內存，但是size大於低端范圍也就是
//起始地址在低端，結束地址超過低端范圍
if (__va(bank->start) < vmalloc_min &&
bank->size > vmalloc_min - __va(bank->start)) {
//banks號大於等於總數量，則直接忽略該bank
//否則將該bank分成兩個bank，高端部分標記成高端
if (meminfo.nr_banks >= NR_BANKS) {
printk(KERN_CRIT "NR_BANKS too low, "
"ignoring high memory\n");
} else {
memmove(bank + 1, bank,
(meminfo.nr_banks - i) * sizeof(*bank));
meminfo.nr_banks++;
i++;
bank[1].size -= vmalloc_min - __va(bank->start);
bank[1].start = __pa(vmalloc_min - 1) + 1;
bank[1].highmem = highmem = 1;
j++;
}
bank->size = vmalloc_min - __va(bank->start);
}
#else
bank->highmem = highmem; //沒定義就賦值為0
/*
* Check whether this memory bank would entirely overlap
* the vmalloc area.
*/
//沒定義高端地址，那麼高端部分全部忽略
if (__va(bank->start) >= vmalloc_min ||
__va(bank->start) < (void *)PAGE_OFFSET) {
printk(KERN_NOTICE "Ignoring RAM at %.8llx-%.8llx "
"(vmalloc region overlap).\n",
(unsigned long long)bank->start,
(unsigned long long)bank->start + bank->size - 1);
continue;
}
/*
* Check whether this memory bank would partially overlap
* the vmalloc area.
*/
if (__va(bank->start + bank->size) > vmalloc_min ||
__va(bank->start + bank->size) < __va(bank->start)) {
unsigned long newsize = vmalloc_min - __va(bank->start);
printk(KERN_NOTICE "Truncating RAM at %.8llx-%.8llx "
"to -%.8llx (vmalloc region overlap).\n",
(unsigned long long)bank->start,
(unsigned long long)bank->start + bank->size - 1,
(unsigned long long)bank->start + newsize - 1);
bank->size = newsize;
}
#endif
if (!bank->highmem && bank->start + bank->size > lowmem_limit)
lowmem_limit = bank->start + bank->size;
j++;
}
#ifdef CONFIG_HIGHMEM
//如果是高端內存，還要進行進一步支持的確認，vipt的不支持
if (highmem) {
const char *reason = NULL;
if (cache_is_vipt_aliasing()) {
/*
* Interactions between kmap and other mappings
* make highmem support with aliasing VIPT caches
* rather difficult.
*/
reason = "with VIPT aliasing cache";
}
if (reason) {
printk(KERN_CRIT "HIGHMEM is not supported %s, ignoring high memory\n",
reason);
while (j > 0 && meminfo.bank[j - 1].highmem)
j--;
}
}
#endif
meminfo.nr_banks = j;
memblock_set_current_limit(lowmem_limit);
}
這裡其中vmalloc_vin 定義為static void * __initdata vmalloc_min = (void *)(VMALLOC_END - SZ_128M);
而vmalloc_end在2440上定義為arch/arm/mach-s3c2410/include/mach/vmalloc.h
#define VMALLOC_END 0xF6000000UL
