/* * Dynamic DMA mapping support for AMD Hammer. * * Use the integrated AGP GART in the Hammer northbridge as an IOMMU for PCI. * This allows to use PCI devices that only support 32bit addresses on systems * with more than 4GB. * * See Documentation/DMA-API-HOWTO.txt for the interface specification. * * Copyright 2002 Andi Kleen, SuSE Labs. * Subject to the GNU General Public License v2 only. */ #include <linux/types.h> #include <linux/ctype.h> #include <linux/agp_backend.h> #include <linux/init.h> #include <linux/mm.h> #include <linux/sched.h> #include <linux/string.h> #include <linux/spinlock.h> #include <linux/pci.h> #include <linux/module.h> #include <linux/topology.h> #include <linux/interrupt.h> #include <linux/bitmap.h> #include <linux/kdebug.h> #include <linux/scatterlist.h> #include <linux/iommu-helper.h> #include <linux/syscore_ops.h> #include <linux/io.h> #include <linux/gfp.h> #include <linux/atomic.h> #include <asm/mtrr.h> #include <asm/pgtable.h> #include <asm/proto.h> #include <asm/iommu.h> #include <asm/gart.h> #include <asm/cacheflush.h> #include <asm/swiotlb.h> #include <asm/dma.h> #include <asm/amd_nb.h> #include <asm/x86_init.h> #include <asm/iommu_table.h> static unsigned long iommu_bus_base; /* GART remapping area (physical) */ static unsigned long iommu_size; /* size of remapping area bytes */ static unsigned long iommu_pages; /* .. and in pages */ static u32 *iommu_gatt_base; /* Remapping table */ static dma_addr_t bad_dma_addr; /* * If this is disabled the IOMMU will use an optimized flushing strategy * of only flushing when an mapping is reused. With it true the GART is * flushed for every mapping. Problem is that doing the lazy flush seems * to trigger bugs with some popular PCI cards, in particular 3ware (but * has been also also seen with Qlogic at least). */ static int iommu_fullflush = 1; /* Allocation bitmap for the remapping area: */ static DEFINE_SPINLOCK(iommu_bitmap_lock); /* Guarded by iommu_bitmap_lock: */ static unsigned long *iommu_gart_bitmap; static u32 gart_unmapped_entry; #define GPTE_VALID 1 #define GPTE_COHERENT 2 #define GPTE_ENCODE(x) \ (((x) & 0xfffff000) | (((x) >> 32) << 4) | GPTE_VALID | GPTE_COHERENT) #define GPTE_DECODE(x) (((x) & 0xfffff000) | (((u64)(x) & 0xff0) << 28)) #define EMERGENCY_PAGES 32 /* = 128KB */ #ifdef CONFIG_AGP #define AGPEXTERN extern #else #define AGPEXTERN #endif /* GART can only remap to physical addresses < 1TB */ #define GART_MAX_PHYS_ADDR (1ULL << 40) /* backdoor interface to AGP driver */ AGPEXTERN int agp_memory_reserved; AGPEXTERN __u32 *agp_gatt_table; static unsigned long next_bit; /* protected by iommu_bitmap_lock */ static bool need_flush; /* global flush state. set for each gart wrap */ static unsigned long alloc_iommu(struct device *dev, int size, unsigned long align_mask) { unsigned long offset, flags; unsigned long boundary_size; unsigned long base_index; base_index = ALIGN(iommu_bus_base & dma_get_seg_boundary(dev), PAGE_SIZE) >> PAGE_SHIFT; boundary_size = ALIGN((u64)dma_get_seg_boundary(dev) + 1, PAGE_SIZE) >> PAGE_SHIFT; spin_lock_irqsave(&iommu_bitmap_lock, flags); offset = iommu_area_alloc(iommu_gart_bitmap, iommu_pages, next_bit, size, base_index, boundary_size, align_mask); if (offset == -1) { need_flush = true; offset = iommu_area_alloc(iommu_gart_bitmap, iommu_pages, 0, size, base_index, boundary_size, align_mask); } if (offset != -1) { next_bit = offset+size; if (next_bit >= iommu_pages) { next_bit = 0; need_flush = true; } } if (iommu_fullflush) need_flush = true; spin_unlock_irqrestore(&iommu_bitmap_lock, flags); return offset; } static void free_iommu(unsigned long offset, int size) { unsigned long flags; spin_lock_irqsave(&iommu_bitmap_lock, flags); bitmap_clear(iommu_gart_bitmap, offset, size); if (offset >= next_bit) next_bit = offset + size; spin_unlock_irqrestore(&iommu_bitmap_lock, flags); } /* * Use global flush state to avoid races with multiple flushers. */ static void flush_gart(void) { unsigned long flags; spin_lock_irqsave(&iommu_bitmap_lock, flags); if (need_flush) { amd_flush_garts(); need_flush = false; } spin_unlock_irqrestore(&iommu_bitmap_lock, flags); } #ifdef CONFIG_IOMMU_LEAK /* Debugging aid for drivers that don't free their IOMMU tables */ static int leak_trace; static int iommu_leak_pages = 20; static void dump_leak(void) { static int dump; if (dump) return; dump = 1; show_stack(NULL, NULL); debug_dma_dump_mappings(NULL); } #endif static void iommu_full(struct device *dev, size_t size, int dir) { /* * Ran out of IOMMU space for this operation. This is very bad. * Unfortunately the drivers cannot handle this operation properly. * Return some non mapped prereserved space in the aperture and * let the Northbridge deal with it. This will result in garbage * in the IO operation. When the size exceeds the prereserved space * memory corruption will occur or random memory will be DMAed * out. Hopefully no network devices use single mappings that big. */ dev_err(dev, "PCI-DMA: Out of IOMMU space for %lu bytes\n", size); if (size > PAGE_SIZE*EMERGENCY_PAGES) { if (dir == PCI_DMA_FROMDEVICE || dir == PCI_DMA_BIDIRECTIONAL) panic("PCI-DMA: Memory would be corrupted\n"); if (dir == PCI_DMA_TODEVICE || dir == PCI_DMA_BIDIRECTIONAL) panic(KERN_ERR "PCI-DMA: Random memory would be DMAed\n"); } #ifdef CONFIG_IOMMU_LEAK dump_leak(); #endif } static inline int need_iommu(struct device *dev, unsigned long addr, size_t size) { return force_iommu || !dma_capable(dev, addr, size); } static inline int nonforced_iommu(struct device *dev, unsigned long addr, size_t size) { return !dma_capable(dev, addr, size); } /* Map a single continuous physical area into the IOMMU. * Caller needs to check if the iommu is needed and flush. */ static dma_addr_t dma_map_area(struct device *dev, dma_addr_t phys_mem, size_t size, int dir, unsigned long align_mask) { unsigned long npages = iommu_num_pages(phys_mem, size, PAGE_SIZE); unsigned long iommu_page; int i; if (unlikely(phys_mem + size > GART_MAX_PHYS_ADDR)) return bad_dma_addr; iommu_page = alloc_iommu(dev, npages, align_mask); if (iommu_page == -1) { if (!nonforced_iommu(dev, phys_mem, size)) return phys_mem; if (panic_on_overflow) panic("dma_map_area overflow %lu bytes\n", size); iommu_full(dev, size, dir); return bad_dma_addr; } for (i = 0; i < npages; i++) { iommu_gatt_base[iommu_page + i] = GPTE_ENCODE(phys_mem); phys_mem += PAGE_SIZE; } return iommu_bus_base + iommu_page*PAGE_SIZE + (phys_mem & ~PAGE_MASK); } /* Map a single area into the IOMMU */ static dma_addr_t gart_map_page(struct device *dev, struct page *page, unsigned long offset, size_t size, enum dma_data_direction dir, struct dma_attrs *attrs) { unsigned long bus; phys_addr_t paddr = page_to_phys(page) + offset; if (!dev) dev = &x86_dma_fallback_dev; if (!need_iommu(dev, paddr, size)) return paddr; bus = dma_map_area(dev, paddr, size, dir, 0); flush_gart(); return bus; } /* * Free a DMA mapping. */ static void gart_unmap_page(struct device *dev, dma_addr_t dma_addr, size_t size, enum dma_data_direction dir, struct dma_attrs *attrs) { unsigned long iommu_page; int npages; int i; if (dma_addr < iommu_bus_base + EMERGENCY_PAGES*PAGE_SIZE || dma_addr >= iommu_bus_base + iommu_size) return; iommu_page = (dma_addr - iommu_bus_base)>>PAGE_SHIFT; npages = iommu_num_pages(dma_addr, size, PAGE_SIZE); for (i = 0; i < npages; i++) { iommu_gatt_base[iommu_page + i] = gart_unmapped_entry; } free_iommu(iommu_page, npages); } /* * Wrapper for pci_unmap_single working with scatterlists. */ static void gart_unmap_sg(struct device *dev, struct scatterlist *sg, int nents, enum dma_data_direction dir, struct dma_attrs *attrs) { struct scatterlist *s; int i; for_each_sg(sg, s, nents, i) { if (!s->dma_length || !s->length) break; gart_unmap_page(dev, s->dma_address, s->dma_length, dir, NULL); } } /* Fallback for dma_map_sg in case of overflow */ static int dma_map_sg_nonforce(struct device *dev, struct scatterlist *sg, int nents, int dir) { struct scatterlist *s; int i; #ifdef CONFIG_IOMMU_DEBUG pr_debug("dma_map_sg overflow\n"); #endif for_each_sg(sg, s, nents, i) { unsigned long addr = sg_phys(s); if (nonforced_iommu(dev, addr, s->length)) { addr = dma_map_area(dev, addr, s->length, dir, 0); if (addr == bad_dma_addr) { if (i > 0) gart_unmap_sg(dev, sg, i, dir, NULL); nents = 0; sg[0].dma_length = 0; break; } } s->dma_address = addr; s->dma_length = s->length; } flush_gart(); return nents; } /* Map multiple scatterlist entries continuous into the first. */ static int __dma_map_cont(struct device *dev, struct scatterlist *start, int nelems, struct scatterlist *sout, unsigned long pages) { unsigned long iommu_start = alloc_iommu(dev, pages, 0); unsigned long iommu_page = iommu_start; struct scatterlist *s; int i; if (iommu_start == -1) return -1; for_each_sg(start, s, nelems, i) { unsigned long pages, addr; unsigned long phys_addr = s->dma_address; BUG_ON(s != start && s->offset); if (s == start) { sout->dma_address = iommu_bus_base; sout->dma_address += iommu_page*PAGE_SIZE + s->offset; sout->dma_length = s->length; } else { sout->dma_length += s->length; } addr = phys_addr; pages = iommu_num_pages(s->offset, s->length, PAGE_SIZE); while (pages--) { iommu_gatt_base[iommu_page] = GPTE_ENCODE(addr); addr += PAGE_SIZE; iommu_page++; } } BUG_ON(iommu_page - iommu_start != pages); return 0; } static inline int dma_map_cont(struct device *dev, struct scatterlist *start, int nelems, struct scatterlist *sout, unsigned long pages, int need) { if (!need) { BUG_ON(nelems != 1); sout->dma_address = start->dma_address; sout->dma_length = start->length; return 0; } return __dma_map_cont(dev, start, nelems, sout, pages); } /* * DMA map all entries in a scatterlist. * Merge chunks that have page aligned sizes into a continuous mapping. */ static int gart_map_sg(struct device *dev, struct scatterlist *sg, int nents, enum dma_data_direction dir, struct dma_attrs *attrs) { struct scatterlist *s, *ps, *start_sg, *sgmap; int need = 0, nextneed, i, out, start; unsigned long pages = 0; unsigned int seg_size; unsigned int max_seg_size; if (nents == 0) return 0; if (!dev) dev = &x86_dma_fallback_dev; out = 0; start = 0; start_sg = sg; sgmap = sg; seg_size = 0; max_seg_size = dma_get_max_seg_size(dev); ps = NULL; /* shut up gcc */ for_each_sg(sg, s, nents, i) { dma_addr_t addr = sg_phys(s); s->dma_address = addr; BUG_ON(s->length == 0); nextneed = need_iommu(dev, addr, s->length); /* Handle the previous not yet processed entries */ if (i > start) { /* * Can only merge when the last chunk ends on a * page boundary and the new one doesn't have an * offset. */ if (!iommu_merge || !nextneed || !need || s->offset || (s->length + seg_size > max_seg_size) || (ps->offset + ps->length) % PAGE_SIZE) { if (dma_map_cont(dev, start_sg, i - start, sgmap, pages, need) < 0) goto error; out++; seg_size = 0; sgmap = sg_next(sgmap); pages = 0; start = i; start_sg = s; } } seg_size += s->length; need = nextneed; pages += iommu_num_pages(s->offset, s->length, PAGE_SIZE); ps = s; } if (dma_map_cont(dev, start_sg, i - start, sgmap, pages, need) < 0) goto error; out++; flush_gart(); if (out < nents) { sgmap = sg_next(sgmap); sgmap->dma_length = 0; } return out; error: flush_gart(); gart_unmap_sg(dev, sg, out, dir, NULL); /* When it was forced or merged try again in a dumb way */ if (force_iommu || iommu_merge) { out = dma_map_sg_nonforce(dev, sg, nents, dir); if (out > 0) return out; } if (panic_on_overflow) panic("dma_map_sg: overflow on %lu pages\n", pages); iommu_full(dev, pages << PAGE_SHIFT, dir); for_each_sg(sg, s, nents, i) s->dma_address = bad_dma_addr; return 0; } /* allocate and map a coherent mapping */ static void * gart_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_addr, gfp_t flag) { dma_addr_t paddr; unsigned long align_mask; struct page *page; if (force_iommu && !(flag & GFP_DMA)) { flag &= ~(__GFP_DMA | __GFP_HIGHMEM | __GFP_DMA32); page = alloc_pages(flag | __GFP_ZERO, get_order(size)); if (!page) return NULL; align_mask = (1UL << get_order(size)) - 1; paddr = dma_map_area(dev, page_to_phys(page), size, DMA_BIDIRECTIONAL, align_mask); flush_gart(); if (paddr != bad_dma_addr) { *dma_addr = paddr; return page_address(page); } __free_pages(page, get_order(size)); } else return dma_generic_alloc_coherent(dev, size, dma_addr, flag); return NULL; } /* free a coherent mapping */ static void gart_free_coherent(struct device *dev, size_t size, void *vaddr, dma_addr_t dma_addr) { gart_unmap_page(dev, dma_addr, size, DMA_BIDIRECTIONAL, NULL); free_pages((unsigned long)vaddr, get_order(size)); } static int gart_mapping_error(struct device *dev, dma_addr_t dma_addr) { return (dma_addr == bad_dma_addr); } static int no_agp; static __init unsigned long check_iommu_size(unsigned long aper, u64 aper_size) { unsigned long a; if (!iommu_size) { iommu_size = aper_size; if (!no_agp) iommu_size /= 2; } a = aper + iommu_size; iommu_size -= round_up(a, PMD_PAGE_SIZE) - a; if (iommu_size < 64*1024*1024) { pr_warning( "PCI-DMA: Warning: Small IOMMU %luMB." " Consider increasing the AGP aperture in BIOS\n", iommu_size >> 20); } return iommu_size; } static __init unsigned read_aperture(struct pci_dev *dev, u32 *size) { unsigned aper_size = 0, aper_base_32, aper_order; u64 aper_base; pci_read_config_dword(dev, AMD64_GARTAPERTUREBASE, &aper_base_32); pci_read_config_dword(dev, AMD64_GARTAPERTURECTL, &aper_order); aper_order = (aper_order >> 1) & 7; aper_base = aper_base_32 & 0x7fff; aper_base <<= 25; aper_size = (32 * 1024 * 1024) << aper_order; if (aper_base + aper_size > 0x100000000UL || !aper_size) aper_base = 0; *size = aper_size; return aper_base; } static void enable_gart_translations(void) { int i; if (!amd_nb_has_feature(AMD_NB_GART)) return; for (i = 0; i < amd_nb_num(); i++) { struct pci_dev *dev = node_to_amd_nb(i)->misc; enable_gart_translation(dev, __pa(agp_gatt_table)); } /* Flush the GART-TLB to remove stale entries */ amd_flush_garts(); } /* * If fix_up_north_bridges is set, the north bridges have to be fixed up on * resume in the same way as they are handled in gart_iommu_hole_init(). */ static bool fix_up_north_bridges; static u32 aperture_order; static u32 aperture_alloc; void set_up_gart_resume(u32 aper_order, u32 aper_alloc) { fix_up_north_bridges = true; aperture_order = aper_order; aperture_alloc = aper_alloc; } static void gart_fixup_northbridges(void) { int i; if (!fix_up_north_bridges) return; if (!amd_nb_has_feature(AMD_NB_GART)) return; pr_info("PCI-DMA: Restoring GART aperture settings\n"); for (i = 0; i < amd_nb_num(); i++) { struct pci_dev *dev = node_to_amd_nb(i)->misc; /* * Don't enable translations just yet. That is the next * step. Restore the pre-suspend aperture settings. */ gart_set_size_and_enable(dev, aperture_order); pci_write_config_dword(dev, AMD64_GARTAPERTUREBASE, aperture_alloc >> 25); } } static void gart_resume(void) { pr_info("PCI-DMA: Resuming GART IOMMU\n"); gart_fixup_northbridges(); enable_gart_translations(); } static struct syscore_ops gart_syscore_ops = { .resume = gart_resume, }; /* * Private Northbridge GATT initialization in case we cannot use the * AGP driver for some reason. */ static __init int init_amd_gatt(struct agp_kern_info *info) { unsigned aper_size, gatt_size, new_aper_size; unsigned aper_base, new_aper_base; struct pci_dev *dev; void *gatt; int i; pr_info("PCI-DMA: Disabling AGP.\n"); aper_size = aper_base = info->aper_size = 0; dev = NULL; for (i = 0; i < amd_nb_num(); i++) { dev = node_to_amd_nb(i)->misc; new_aper_base = read_aperture(dev, &new_aper_size); if (!new_aper_base) goto nommu; if (!aper_base) { aper_size = new_aper_size; aper_base = new_aper_base; } if (aper_size != new_aper_size || aper_base != new_aper_base) goto nommu; } if (!aper_base) goto nommu; info->aper_base = aper_base; info->aper_size = aper_size >> 20; gatt_size = (aper_size >> PAGE_SHIFT) * sizeof(u32); gatt = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, get_order(gatt_size)); if (!gatt) panic("Cannot allocate GATT table"); if (set_memory_uc((unsigned long)gatt, gatt_size >> PAGE_SHIFT)) panic("Could not set GART PTEs to uncacheable pages"); agp_gatt_table = gatt; register_syscore_ops(&gart_syscore_ops); flush_gart(); pr_info("PCI-DMA: aperture base @ %x size %u KB\n", aper_base, aper_size>>10); return 0; nommu: /* Should not happen anymore */ pr_warning("PCI-DMA: More than 4GB of RAM and no IOMMU\n" "falling back to iommu=soft.\n"); return -1; } static struct dma_map_ops gart_dma_ops = { .map_sg = gart_map_sg, .unmap_sg = gart_unmap_sg, .map_page = gart_map_page, .unmap_page = gart_unmap_page, .alloc_coherent = gart_alloc_coherent, .free_coherent = gart_free_coherent, .mapping_error = gart_mapping_error, }; static void gart_iommu_shutdown(void) { struct pci_dev *dev; int i; /* don't shutdown it if there is AGP installed */ if (!no_agp) return; if (!amd_nb_has_feature(AMD_NB_GART)) return; for (i = 0; i < amd_nb_num(); i++) { u32 ctl; dev = node_to_amd_nb(i)->misc; pci_read_config_dword(dev, AMD64_GARTAPERTURECTL, &ctl); ctl &= ~GARTEN; pci_write_config_dword(dev, AMD64_GARTAPERTURECTL, ctl); } } int __init gart_iommu_init(void) { struct agp_kern_info info; unsigned long iommu_start; unsigned long aper_base, aper_size; unsigned long start_pfn, end_pfn; unsigned long scratch; long i; if (!amd_nb_has_feature(AMD_NB_GART)) return 0; #ifndef CONFIG_AGP_AMD64 no_agp = 1; #else /* Makefile puts PCI initialization via subsys_initcall first. */ /* Add other AMD AGP bridge drivers here */ no_agp = no_agp || (agp_amd64_init() < 0) || (agp_copy_info(agp_bridge, &info) < 0); #endif if (no_iommu || (!force_iommu && max_pfn <= MAX_DMA32_PFN) || !gart_iommu_aperture || (no_agp && init_amd_gatt(&info) < 0)) { if (max_pfn > MAX_DMA32_PFN) { pr_warning("More than 4GB of memory but GART IOMMU not available.\n"); pr_warning("falling back to iommu=soft.\n"); } return 0; } /* need to map that range */ aper_size = info.aper_size << 20; aper_base = info.aper_base; end_pfn = (aper_base>>PAGE_SHIFT) + (aper_size>>PAGE_SHIFT); if (end_pfn > max_low_pfn_mapped) { start_pfn = (aper_base>>PAGE_SHIFT); init_memory_mapping(start_pfn<<PAGE_SHIFT, end_pfn<<PAGE_SHIFT); } pr_info("PCI-DMA: using GART IOMMU.\n"); iommu_size = check_iommu_size(info.aper_base, aper_size); iommu_pages = iommu_size >> PAGE_SHIFT; iommu_gart_bitmap = (void *) __get_free_pages(GFP_KERNEL | __GFP_ZERO, get_order(iommu_pages/8)); if (!iommu_gart_bitmap) panic("Cannot allocate iommu bitmap\n"); #ifdef CONFIG_IOMMU_LEAK if (leak_trace) { int ret; ret = dma_debug_resize_entries(iommu_pages); if (ret) pr_debug("PCI-DMA: Cannot trace all the entries\n"); } #endif /* * Out of IOMMU space handling. * Reserve some invalid pages at the beginning of the GART. */ bitmap_set(iommu_gart_bitmap, 0, EMERGENCY_PAGES); pr_info("PCI-DMA: Reserving %luMB of IOMMU area in the AGP aperture\n", iommu_size >> 20); agp_memory_reserved = iommu_size; iommu_start = aper_size - iommu_size; iommu_bus_base = info.aper_base + iommu_start; bad_dma_addr = iommu_bus_base; iommu_gatt_base = agp_gatt_table + (iommu_start>>PAGE_SHIFT); /* * Unmap the IOMMU part of the GART. The alias of the page is * always mapped with cache enabled and there is no full cache * coherency across the GART remapping. The unmapping avoids * automatic prefetches from the CPU allocating cache lines in * there. All CPU accesses are done via the direct mapping to * the backing memory. The GART address is only used by PCI * devices. */ set_memory_np((unsigned long)__va(iommu_bus_base), iommu_size >> PAGE_SHIFT); /* * Tricky. The GART table remaps the physical memory range, * so the CPU wont notice potential aliases and if the memory * is remapped to UC later on, we might surprise the PCI devices * with a stray writeout of a cacheline. So play it sure and * do an explicit, full-scale wbinvd() _after_ having marked all * the pages as Not-Present: */ wbinvd(); /* * Now all caches are flushed and we can safely enable * GART hardware. Doing it early leaves the possibility * of stale cache entries that can lead to GART PTE * errors. */ enable_gart_translations(); /* * Try to workaround a bug (thanks to BenH): * Set unmapped entries to a scratch page instead of 0. * Any prefetches that hit unmapped entries won't get an bus abort * then. (P2P bridge may be prefetching on DMA reads). */ scratch = get_zeroed_page(GFP_KERNEL); if (!scratch) panic("Cannot allocate iommu scratch page"); gart_unmapped_entry = GPTE_ENCODE(__pa(scratch)); for (i = EMERGENCY_PAGES; i < iommu_pages; i++) iommu_gatt_base[i] = gart_unmapped_entry; flush_gart(); dma_ops = &gart_dma_ops; x86_platform.iommu_shutdown = gart_iommu_shutdown; swiotlb = 0; return 0; } void __init gart_parse_options(char *p) { int arg; #ifdef CONFIG_IOMMU_LEAK if (!strncmp(p, "leak", 4)) { leak_trace = 1; p += 4; if (*p == '=') ++p; if (isdigit(*p) && get_option(&p, &arg)) iommu_leak_pages = arg; } #endif if (isdigit(*p) && get_option(&p, &arg)) iommu_size = arg; if (!strncmp(p, "fullflush", 9)) iommu_fullflush = 1; if (!strncmp(p, "nofullflush", 11)) iommu_fullflush = 0; if (!strncmp(p, "noagp", 5)) no_agp = 1; if (!strncmp(p, "noaperture", 10)) fix_aperture = 0; /* duplicated from pci-dma.c */ if (!strncmp(p, "force", 5)) gart_iommu_aperture_allowed = 1; if (!strncmp(p, "allowed", 7)) gart_iommu_aperture_allowed = 1; if (!strncmp(p, "memaper", 7)) { fallback_aper_force = 1; p += 7; if (*p == '=') { ++p; if (get_option(&p, &arg)) fallback_aper_order = arg; } } } IOMMU_INIT_POST(gart_iommu_hole_init);