WhyCan Forum(哇酷开发者社区)

static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata)
{
	struct page *page;
	unsigned long start, end, pages, count = 0;

	if (!bdata->node_bootmem_map)
		return 0;

	start = bdata->node_min_pfn;
	end = bdata->node_low_pfn;

	printk(KERN_NOTICE"nid=%td start=%lx end=%lx\n",
		bdata - bootmem_node_data, start, end);

	while (start < end) {
		unsigned long *map, idx, vec;

		map = bdata->node_bootmem_map;
		idx = start - bdata->node_min_pfn;
		vec = ~map[idx / BITS_PER_LONG];
		/*
		 * If we have a properly aligned and fully unreserved
		 * BITS_PER_LONG block of pages in front of us, free
		 * it in one go.
		 */
		if (IS_ALIGNED(start, BITS_PER_LONG) && vec == ~0UL) {
			int order = ilog2(BITS_PER_LONG);
			if(start==0x46400){ //保留uboot framebuffer所用的页面 andrew AICHIP 2021.1.2
				//因为我的屏幕是480*272的，所以保留BITS_PER_LONG*4就够了。
				count += BITS_PER_LONG*4;
				start += BITS_PER_LONG*4;
			}
			__free_pages_bootmem(pfn_to_page(start), order);
			count += BITS_PER_LONG;
			start += BITS_PER_LONG;
		} else {
			unsigned long off = 0;

			while (vec && off < BITS_PER_LONG) {
				if (vec & 1) {
					page = pfn_to_page(start + off);
					__free_pages_bootmem(page, 0);
					count++;
				}
				vec >>= 1;
				off++;
			}
			start = ALIGN(start + 1, BITS_PER_LONG);
		}
	}

	page = virt_to_page(bdata->node_bootmem_map);
	pages = bdata->node_low_pfn - bdata->node_min_pfn;
	pages = bootmem_bootmap_pages(pages);
	count += pages;
	while (pages--)
		__free_pages_bootmem(page++, 0);

	bdebug("nid=%td released=%lx\n", bdata - bootmem_node_data, count);

	return count;
}