struct resource {

    resource_size_t start;

    resource_size_t end;

    const char *name;

    unsigned long flags;

    struct resource *parent, *sibling, *child;

};

/arch/arm/kernel/setup.c/

static struct resource mem_res[] = {

    {

        .name = "Video RAM",

        .start = ,

        .end = ,

        .flags = IORESOURCE_MEM

    },

    {

        .name = "Kernel text",

        .start = ,

        .end = ,

        .flags = IORESOURCE_MEM

    },

    {

        .name = "Kernel data",

        .start = ,

        .end = ,

        .flags = IORESOURCE_MEM

    }

};

#define video_ram   mem_res[0]

#define kernel_code mem_res[1]

#define kernel_data mem_res[2]

int request_resource(struct resource *root, struct resource *new)

    -->__request_resource(root, new);//按地址升序排列

/* Return the conflict entry if you can't request it */

static struct resource * __request_resource(struct resource *root, struct resource *new)

{

    resource_size_t start = new->start;

    resource_size_t end = new->end;

    struct resource *tmp, **p;

    if (end < start)

        return root;

    if (start < root->start)

        return root;

    if (end > root->end)

        return root;

    p = &root->child;

    for (;;) {

        tmp = *p;

        if (!tmp || tmp->start > end) {

            new->sibling = tmp;

            *p = new;

            new->parent = root;

            return NULL;

        }

        p = &tmp->sibling;

        if (tmp->end < start)

            continue;

        return tmp;

    }

}