early_init_fdt_scan_reserved_mem
kenrel: 5.10
arch: arm64
early_init_fdt_scan_reserved_mem查找到“reserved-memory”的节点，将每个子节点中的区域加到memblock.reserverd中，同时根据nomap属性如果有定义，则还要从memblock.memory中删除
/**
* early_init_fdt_scan_reserved_mem() - create reserved memory regions
*
* This function grabs memory from early allocator for device exclusive use
* defined in device tree structures. It should be called by arch specific code
* once the early allocator (i.e. memblock) has been fully activated.
*/
void __init early_init_fdt_scan_reserved_mem(void)
{
int n;
u64 base, size;
if (!initial_boot_params)
return;
/* Process header /memreserve/ fields */
for (n = 0; ; n++) {
fdt_get_mem_rsv(initial_boot_params, n, &base, &size);
if (!size)
break;
early_init_dt_reserve_memory_arch(base, size, false);
}
of_scan_flat_dt(__fdt_scan_reserved_mem, NULL);
fdt_init_reserved_mem();
}
- 遍历reserved memory节点的每个child node，通过fdt_get_mem_rsv获取预留的物理地址和大小，通过early_init_dt_reserve_memory_arch插入到memblock.reserved中
int fdt_get_mem_rsv(const void *fdt, int n, uint64_t *address, uint64_t *size)
{
const struct fdt_reserve_entry *re;
FDT_RO_PROBE(fdt);
re = fdt_mem_rsv(fdt, n);
if (!can_assume(VALID_INPUT) && !re)
return -FDT_ERR_BADOFFSET;
*address = fdt64_ld(&re->address);
*size = fdt64_ld(&re->size);
return 0;
}
fdt代表dtb所在的虚拟地址，fdt_get_mem_rsv将fdt中第n个reserved memory节点的物理地址和大小保存在address和size中
int __init __weak early_init_dt_reserve_memory_arch(phys_addr_t base,
phys_addr_t size, bool nomap)
{
if (nomap)
return memblock_remove(base, size);
return memblock_reserve(base, size);
}
对于reserved memory节点下带有nomap属性的child node，通过memblock_remove将预留的物理地址区域从memblock.memory中删除，并添加到memblock.reserved区域
-
通过of_scan_flat_dt遍历fdt的每个node，对其执行__fdt_scan_reserved_mem，它会查找到“reserved-memory”的节点，将每个子节点中的区域加到memblock.reserverd中，同时根据nomap属性如果有定义，则还要从memblock.memory中删除
-
fdt_init_reserved_mem
reserved memory节点下的每一个子节点会对应一个reserved_mem，fdt_init_reserved_mem会遍历每一个reserved_mem，对其执行__reserved_mem_init_node。__reserved_mem_init_node通过将RESERVEDMEM_OF_DECLARE声明的of_device_id与reserved_mem 的compatible属性进行匹配，匹配成功则执行声明的回调，对于cma这个回调函数就是rmem_cma_setup，他会通过reserved_mem来初始化一个cma
/**
* fdt_init_reserved_mem() - allocate and init all saved reserved memory regions
*/
void __init fdt_init_reserved_mem(void)
{
int i;
/* check for overlapping reserved regions */
__rmem_check_for_overlap();
for (i = 0; i < reserved_mem_count; i++) {
struct reserved_mem *rmem = &reserved_mem[i];
unsigned long node = rmem->fdt_node;
int len;
const __be32 *prop;
int err = 0;
bool nomap;
nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
prop = of_get_flat_dt_prop(node, "phandle", &len);
if (!prop)
prop = of_get_flat_dt_prop(node, "linux,phandle", &len);
if (prop)
rmem->phandle = of_read_number(prop, len/4);
if (rmem->size == 0)
err = __reserved_mem_alloc_size(node, rmem->name,
&rmem->base, &rmem->size);
if (err == 0) {
err = __reserved_mem_init_node(rmem);
if (err != 0 && err != -ENOENT) {
pr_info("node %s compatible matching fail\n",
rmem->name);
memblock_free(rmem->base, rmem->size);
if (nomap)
memblock_add(rmem->base, rmem->size);
}
}
}
}