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- // SPDX-License-Identifier: GPL-2.0
- #include <linux/ioport.h>
- #include <linux/printk.h>
- #include <asm/e820/api.h>
- #include <asm/pci_x86.h>
- static void resource_clip(struct resource *res, resource_size_t start,
- resource_size_t end)
- {
- resource_size_t low = 0, high = 0;
- if (res->end < start || res->start > end)
- return; /* no conflict */
- if (res->start < start)
- low = start - res->start;
- if (res->end > end)
- high = res->end - end;
- /* Keep the area above or below the conflict, whichever is larger */
- if (low > high)
- res->end = start - 1;
- else
- res->start = end + 1;
- }
- static void remove_e820_regions(struct resource *avail)
- {
- int i;
- struct e820_entry *entry;
- u64 e820_start, e820_end;
- struct resource orig = *avail;
- if (!pci_use_e820)
- return;
- for (i = 0; i < e820_table->nr_entries; i++) {
- entry = &e820_table->entries[i];
- e820_start = entry->addr;
- e820_end = entry->addr + entry->size - 1;
- resource_clip(avail, e820_start, e820_end);
- if (orig.start != avail->start || orig.end != avail->end) {
- pr_info("clipped %pR to %pR for e820 entry [mem %#010Lx-%#010Lx]\n",
- &orig, avail, e820_start, e820_end);
- orig = *avail;
- }
- }
- }
- void arch_remove_reservations(struct resource *avail)
- {
- /*
- * Trim out BIOS area (high 2MB) and E820 regions. We do not remove
- * the low 1MB unconditionally, as this area is needed for some ISA
- * cards requiring a memory range, e.g. the i82365 PCMCIA controller.
- */
- if (avail->flags & IORESOURCE_MEM) {
- resource_clip(avail, BIOS_ROM_BASE, BIOS_ROM_END);
- remove_e820_regions(avail);
- }
- }
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