/*
* 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-mapping.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/string.h>
#include <linux/spinlock.h>
#include <linux/pci.h>
#include <linux/module.h>
#include <linux/topology.h>
#include <linux/interrupt.h>
#include <linux/bitops.h>
#include <linux/kdebug.h>
#include <linux/scatterlist.h>
#include <linux/iommu-helper.h>
#include <linux/sysdev.h>
#include <asm/atomic.h>
#include <asm/io.h>
#include <asm/mtrr.h>
#include <asm/pgtable.h>
#include <asm/proto.h>
#include <asm/gart.h>
#include <asm/cacheflush.h>
#include <asm/swiotlb.h>
#include <asm/dma.h>
#include <asm/k8.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 */
/*
* 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).
*/
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 to_pages(addr, size) \
(round_up(((addr) & ~PAGE_MASK) + (size), PAGE_SIZE) >> PAGE_SHIFT)
#define EMERGENCY_PAGES 32 /* = 128KB */
#ifdef CONFIG_AGP
#define AGPEXTERN extern
#else
#define AGPEXTERN
#endif
/* 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 int need_flush; /* global flush state. set for each gart wrap */
static unsigned long alloc_iommu(struct device *dev, int size)
{
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(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, 0);
if (offset == -1) {
need_flush = 1;
offset = iommu_area_alloc(iommu_gart_bitmap, iommu_pages, 0,
size, base_index, boundary_size, 0);
}
if (offset != -1) {
set_bit_string(iommu_gart_bitmap, offset, size);
next_bit = offset+size;
if (next_bit >= iommu_pages) {
next_bit = 0;
need_flush = 1;
}
}
if (iommu_fullflush)
need_flush = 1;
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);
iommu_area_free(iommu_gart_bitmap, 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) {
k8_flush_garts();
need_flush = 0;
}
spin_unlock_irqrestore(&iommu_bitmap_lock, flags);
}
#ifdef CONFIG_IOMMU_LEAK
#define SET_LEAK(x) \
do { \
if (iommu_leak_tab) \
iommu_leak_tab[x] = __builtin_return_address(0);\
} while (0)
#define CLEAR_LEAK(x) \
do { \
if (iommu_leak_tab) \
iommu_leak_tab[x] = NULL; \
} while (0)
/* Debugging aid for drivers that don't free their IOMMU tables */
static void **iommu_leak_tab;
static int leak_trace;
static int iommu_leak_pages = 20;
static void dump_leak(void)
{
int i;
static int dump;
if (dump || !iommu_leak_tab)
return;
dump = 1;
show_stack(NULL, NULL);
/* Very crude. dump some from the end of the table too */
printk(KERN_DEBUG "Dumping %d pages from end of IOMMU:\n",
iommu_leak_pages);
for (i = 0; i < iommu_leak_pages; i += 2) {
printk(KERN_DEBUG "%lu: ", iommu_pages-i);
printk_address((unsigned long) iommu_leak_tab[iommu_pages-i], 0);
printk(KERN_CONT "%c", (i+1)%2 == 0 ? '\n' : ' ');
}
printk(KERN_DEBUG "\n");
}
#else
# define SET_LEAK(x)
# define CLEAR_LEAK(x)
#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.
*/
printk(KERN_ERR
"PCI-DMA: Out of IOMMU space for %lu bytes at device %s\n",
size, dev->bus_id);
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)
{
u64 mask = *dev->dma_mask;
int high = addr + size > mask;
int mmu = high;
if (force_iommu)
mmu = 1;
return mmu;
}
static inline int
nonforced_iommu(struct device *dev, unsigned long addr, size_t size)
{
u64 mask = *dev->dma_mask;
int high = addr + size > mask;
int mmu = high;
return mmu;
}
/* 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 npages = to_pages(phys_mem, size);
unsigned long iommu_page = alloc_iommu(dev, npages);
int i;
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_address;
}
for (i = 0; i < npages; i++) {
iommu_gatt_base[iommu_page + i] = GPTE_ENCODE(phys_mem);
SET_LEAK(iommu_page + i);
phys_mem += PAGE_SIZE;
}
return iommu_bus_base + iommu_page*PAGE_SIZE + (phys_mem & ~PAGE_MASK);
}
static dma_addr_t
gart_map_simple(struct device *dev, phys_addr_t paddr, size_t size, int dir)
{
dma_addr_t map = dma_map_area(dev, paddr, size, dir);
flush_gart();
return map;
}
/* Map a single area into the IOMMU */
static dma_addr_t
gart_map_single(struct device *dev, phys_addr_t paddr, size_t size, int dir)
{
unsigned long bus;
if (!dev)
dev = &fallback_dev;
if (!need_iommu(dev, paddr, size))
return paddr;
bus = gart_map_simple(dev, paddr, size, dir);
return bus;
}
/*
* Free a DMA mapping.
*/
static void gart_unmap_single(struct device *dev, dma_addr_t dma_addr,
size_t size, int direction)
{
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 = to_pages(dma_addr, size);
for (i = 0; i < npages; i++) {
iommu_gatt_base[iommu_page + i] = gart_unmapped_entry;
CLEAR_LEAK(iommu_page + i);
}
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, int dir)
{
struct scatterlist *s;
int i;
for_each_sg(sg, s, nents, i) {
if (!s->dma_length || !s->length)
break;
gart_unmap_single(dev, s->dma_address, s->dma_length, dir);
}
}
/* 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
printk(KERN_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);
if (addr == bad_dma_address) {
if (i > 0)
gart_unmap_sg(dev, sg, i, dir);
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);
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 = to_pages(s->offset, s->length);
while (pages--) {
iommu_gatt_base[iommu_page] = GPTE_ENCODE(addr);
SET_LEAK(iommu_page);
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, int dir)
{
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 = &fallback_dev;
out = 0;
start = 0;
start_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 += to_pages(s->offset, s->length);
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);
/* 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_address;
return 0;
}
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) {
printk(KERN_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, 0x94, &aper_base_32);
pci_read_config_dword(dev, 0x90, &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 int gart_resume(struct sys_device *dev)
{
return 0;
}
static int gart_suspend(struct sys_device *dev, pm_message_t state)
{
return -EINVAL;
}
static struct sysdev_class gart_sysdev_class = {
.name = "gart",
.suspend = gart_suspend,
.resume = gart_resume,
};
static struct sys_device device_gart = {
.id = 0,
.cls = &gart_sysdev_class,
};
/*
* Private Northbridge GATT initialization in case we cannot use the
* AGP driver for some reason.
*/
static __init int init_k8_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, error;
printk(KERN_INFO "PCI-DMA: Disabling AGP.\n");
aper_size = aper_base = info->aper_size = 0;
dev = NULL;
for (i = 0; i < num_k8_northbridges; i++) {
dev = k8_northbridges[i];
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, 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");
memset(gatt, 0, gatt_size);
agp_gatt_table = gatt;
for (i = 0; i < num_k8_northbridges; i++) {
u32 gatt_reg;
u32 ctl;
dev = k8_northbridges[i];
gatt_reg = __pa(gatt) >> 12;
gatt_reg <<= 4;
pci_write_config_dword(dev, 0x98, gatt_reg);
pci_read_config_dword(dev, 0x90, &ctl);
ctl |= 1;
ctl &= ~((1<<4) | (1<<5));
pci_write_config_dword(dev, 0x90, ctl);
}
error = sysdev_class_register(&gart_sysdev_class);
if (!error)
error = sysdev_register(&device_gart);
if (error)
panic("Could not register gart_sysdev -- would corrupt data on next suspend");
flush_gart();
printk(KERN_INFO "PCI-DMA: aperture base @ %x size %u KB\n",
aper_base, aper_size>>10);
return 0;
nommu:
/* Should not happen anymore */
printk(KERN_WARNING "PCI-DMA: More than 4GB of RAM and no IOMMU\n"
KERN_WARNING "falling back to iommu=soft.\n");
return -1;
}
extern int agp_amd64_init(void);
static const struct dma_mapping_ops gart_dma_ops = {
.mapping_error = NULL,
.map_single = gart_map_single,
.map_simple = gart_map_simple,
.unmap_single = gart_unmap_single,
.sync_single_for_cpu = NULL,
.sync_single_for_device = NULL,
.sync_single_range_for_cpu = NULL,
.sync_single_range_for_device = NULL,
.sync_sg_for_cpu = NULL,
.sync_sg_for_device = NULL,
.map_sg = gart_map_sg,
.unmap_sg = gart_unmap_sg,
};
void gart_iommu_shutdown(void)
{
struct pci_dev *dev;
int i;
if (no_agp && (dma_ops != &gart_dma_ops))
return;
for (i = 0; i < num_k8_northbridges; i++) {
u32 ctl;
dev = k8_northbridges[i];
pci_read_config_dword(dev, 0x90, &ctl);
ctl &= ~1;
pci_write_config_dword(dev, 0x90, ctl);
}
}
void __init gart_iommu_init(void)
{
struct agp_kern_info info;
unsigned long iommu_start;
unsigned long aper_size;
unsigned long scratch;
long i;
if (cache_k8_northbridges() < 0 || num_k8_northbridges == 0) {
printk(KERN_INFO "PCI-GART: No AMD northbridge found.\n");
return;
}
#ifndef CONFIG_AGP_AMD64
no_agp = 1;
#else
/* Makefile puts PCI initialization via subsys_initcall first. */
/* Add other K8 AGP bridge drivers here */
no_agp = no_agp ||
(agp_amd64_init() < 0) ||
(agp_copy_info(agp_bridge, &info) < 0);
#endif
if (swiotlb)
return;
/* Did we detect a different HW IOMMU? */
if (iommu_detected && !gart_iommu_aperture)
return;
if (no_iommu ||
(!force_iommu && end_pfn <= MAX_DMA32_PFN) ||
!gart_iommu_aperture ||
(no_agp && init_k8_gatt(&info) < 0)) {
if (end_pfn > MAX_DMA32_PFN) {
printk(KERN_WARNING "More than 4GB of memory "
"but GART IOMMU not available.\n"
KERN_WARNING "falling back to iommu=soft.\n");
}
return;
}
printk(KERN_INFO "PCI-DMA: using GART IOMMU.\n");
aper_size = info.aper_size * 1024 * 1024;
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,
get_order(iommu_pages/8));
if (!iommu_gart_bitmap)
panic("Cannot allocate iommu bitmap\n");
memset(iommu_gart_bitmap, 0, iommu_pages/8);
#ifdef CONFIG_IOMMU_LEAK
if (leak_trace) {
iommu_leak_tab = (void *)__get_free_pages(GFP_KERNEL,
get_order(iommu_pages*sizeof(void *)));
if (iommu_leak_tab)
memset(iommu_leak_tab, 0, iommu_pages * 8);
else
printk(KERN_DEBUG
"PCI-DMA: Cannot allocate leak trace area\n");
}
#endif
/*
* Out of IOMMU space handling.
* Reserve some invalid pages at the beginning of the GART.
*/
set_bit_string(iommu_gart_bitmap, 0, EMERGENCY_PAGES);
agp_memory_reserved = iommu_size;
printk(KERN_INFO
"PCI-DMA: Reserving %luMB of IOMMU area in the AGP aperture\n",
iommu_size >> 20);
iommu_start = aper_size - iommu_size;
iommu_bus_base = info.aper_base + iommu_start;
bad_dma_address = 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();
/*
* 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.
*/
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;
}
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", 8))
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;
}
}
}
