From 49c2fa08a77a7eefa4cbc73601f64984aceacfa7 Mon Sep 17 00:00:00 2001 From: Neil Horman Date: Wed, 8 Dec 2010 09:47:48 -0500 Subject: PCI: Update MCP55 quirk to not affect non HyperTransport variants MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit I wrote this quirk awhile ago to properly setup MCP55 chips on hypertransport busses so that interrupts reached whatever cpu happend to boot the kdump kernel. while that works well, it was recently shown to me that a a non-hypertransport variant of the MCP55 exists, and on those system the register that this quirk manipulates causes hangs if you write to it. Since the quirk was only meant to handle errors found on MCP55 chips that have a HT interface, this patch adds a filter to make sure the chip is an HT capable before making the needed register adjustment. This lets the broken MCP55s work with kdump while not breaking the non-HT variants. Resolves https://bugzilla.kernel.org/show_bug.cgi?id=23952 Tested successfully by the reporter and myself. Cc: stable@kernel.org Reported-by: Mathieu Bérard Acked-by: Vivek Goyal Signed-off-by: Neil Horman Signed-off-by: Jesse Barnes --- drivers/pci/quirks.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c index 6f9350c..313c0bd 100644 --- a/drivers/pci/quirks.c +++ b/drivers/pci/quirks.c @@ -2329,6 +2329,9 @@ static void __devinit nvbridge_check_legacy_irq_routing(struct pci_dev *dev) { u32 cfg; + if (!pci_find_capability(dev, PCI_CAP_ID_HT)) + return; + pci_read_config_dword(dev, 0x74, &cfg); if (cfg & ((1 << 2) | (1 << 15))) { -- cgit v1.1 From ac57cd5ee1935d1e60de86d75f13f377775f1c96 Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Thu, 16 Dec 2010 10:38:20 -0700 Subject: Revert "PCI: fix pci_bus_alloc_resource() hang, prefer positive decode" This reverts commit 82e3e767c21fef2b1b38868e20eb4e470a1e38e3. We're going back to considering bus resources in the order we found them (in _CRS order, when we're using _CRS), so we don't need to define any ordering. Acked-by: H. Peter Anvin Signed-off-by: Bjorn Helgaas Signed-off-by: Jesse Barnes --- drivers/pci/bus.c | 70 +++++++++++++++++-------------------------------------- 1 file changed, 21 insertions(+), 49 deletions(-) diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c index 003170e..5624db8 100644 --- a/drivers/pci/bus.c +++ b/drivers/pci/bus.c @@ -64,57 +64,17 @@ void pci_bus_remove_resources(struct pci_bus *bus) } } -static bool pci_bus_resource_better(struct resource *res1, bool pos1, - struct resource *res2, bool pos2) -{ - /* If exactly one is positive decode, always prefer that one */ - if (pos1 != pos2) - return pos1 ? true : false; - - /* Prefer the one that contains the highest address */ - if (res1->end != res2->end) - return (res1->end > res2->end) ? true : false; - - /* Otherwise, prefer the one with highest "center of gravity" */ - if (res1->start != res2->start) - return (res1->start > res2->start) ? true : false; - - /* Otherwise, choose one arbitrarily (but consistently) */ - return (res1 > res2) ? true : false; -} - -static bool pci_bus_resource_positive(struct pci_bus *bus, struct resource *res) -{ - struct pci_bus_resource *bus_res; - - /* - * This relies on the fact that pci_bus.resource[] refers to P2P or - * CardBus bridge base/limit registers, which are always positively - * decoded. The pci_bus.resources list contains host bridge or - * subtractively decoded resources. - */ - list_for_each_entry(bus_res, &bus->resources, list) { - if (bus_res->res == res) - return (bus_res->flags & PCI_SUBTRACTIVE_DECODE) ? - false : true; - } - return true; -} - /* - * Find the next-best bus resource after the cursor "res". If the cursor is - * NULL, return the best resource. "Best" means that we prefer positive - * decode regions over subtractive decode, then those at higher addresses. + * Find the highest-address bus resource below the cursor "res". If the + * cursor is NULL, return the highest resource. */ static struct resource *pci_bus_find_resource_prev(struct pci_bus *bus, unsigned int type, struct resource *res) { - bool res_pos, r_pos, prev_pos = false; struct resource *r, *prev = NULL; int i; - res_pos = pci_bus_resource_positive(bus, res); pci_bus_for_each_resource(bus, r, i) { if (!r) continue; @@ -122,14 +82,26 @@ static struct resource *pci_bus_find_resource_prev(struct pci_bus *bus, if ((r->flags & IORESOURCE_TYPE_BITS) != type) continue; - r_pos = pci_bus_resource_positive(bus, r); - if (!res || pci_bus_resource_better(res, res_pos, r, r_pos)) { - if (!prev || pci_bus_resource_better(r, r_pos, - prev, prev_pos)) { - prev = r; - prev_pos = r_pos; - } + /* If this resource is at or past the cursor, skip it */ + if (res) { + if (r == res) + continue; + if (r->end > res->end) + continue; + if (r->end == res->end && r->start > res->start) + continue; } + + if (!prev) + prev = r; + + /* + * A small resource is higher than a large one that ends at + * the same address. + */ + if (r->end > prev->end || + (r->end == prev->end && r->start > prev->start)) + prev = r; } return prev; -- cgit v1.1 From 5e52f1c5e85fdc3831eeae8b546577e94a586f81 Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Thu, 16 Dec 2010 10:38:25 -0700 Subject: Revert "x86: allocate space within a region top-down" This reverts commit 1af3c2e45e7a641e774bbb84fa428f2f0bf2d9c9. Acked-by: H. Peter Anvin Signed-off-by: Bjorn Helgaas Signed-off-by: Jesse Barnes --- arch/x86/kernel/setup.c | 1 - 1 file changed, 1 deletion(-) diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 21c6746..85268f8 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -769,7 +769,6 @@ void __init setup_arch(char **cmdline_p) x86_init.oem.arch_setup(); - resource_alloc_from_bottom = 0; iomem_resource.end = (1ULL << boot_cpu_data.x86_phys_bits) - 1; setup_memory_map(); parse_setup_data(); -- cgit v1.1 From d14125ecfee05473de46f06d992db109308c57a3 Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Thu, 16 Dec 2010 10:38:31 -0700 Subject: Revert "x86/PCI: allocate space from the end of a region, not the beginning" This reverts commit dc9887dc02e37bcf83f4e792aa14b07782ef54cf. Acked-by: H. Peter Anvin Signed-off-by: Bjorn Helgaas Signed-off-by: Jesse Barnes --- arch/x86/pci/i386.c | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-) diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c index c4bb261c..8379c2c 100644 --- a/arch/x86/pci/i386.c +++ b/arch/x86/pci/i386.c @@ -65,21 +65,16 @@ pcibios_align_resource(void *data, const struct resource *res, resource_size_t size, resource_size_t align) { struct pci_dev *dev = data; - resource_size_t start = round_down(res->end - size + 1, align); + resource_size_t start = res->start; if (res->flags & IORESOURCE_IO) { - - /* - * If we're avoiding ISA aliases, the largest contiguous I/O - * port space is 256 bytes. Clearing bits 9 and 10 preserves - * all 256-byte and smaller alignments, so the result will - * still be correctly aligned. - */ - if (!skip_isa_ioresource_align(dev)) - start &= ~0x300; + if (skip_isa_ioresource_align(dev)) + return start; + if (start & 0x300) + start = (start + 0x3ff) & ~0x3ff; } else if (res->flags & IORESOURCE_MEM) { if (start < BIOS_END) - start = res->end; /* fail; no space */ + start = BIOS_END; } return start; } -- cgit v1.1 From 6db45b76eaa08133187f2cb44d496de7e9503aa8 Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Thu, 16 Dec 2010 10:38:36 -0700 Subject: Revert "PCI: allocate bus resources from the top down" This reverts commit b126b4703afa4010b161784a43650337676dd03b. We're going back to the old behavior of allocating from bus resources in _CRS order. Acked-by: H. Peter Anvin Signed-off-by: Bjorn Helgaas Signed-off-by: Jesse Barnes --- drivers/pci/bus.c | 53 +++++------------------------------------------------ 1 file changed, 5 insertions(+), 48 deletions(-) diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c index 5624db8..69546e9 100644 --- a/drivers/pci/bus.c +++ b/drivers/pci/bus.c @@ -64,49 +64,6 @@ void pci_bus_remove_resources(struct pci_bus *bus) } } -/* - * Find the highest-address bus resource below the cursor "res". If the - * cursor is NULL, return the highest resource. - */ -static struct resource *pci_bus_find_resource_prev(struct pci_bus *bus, - unsigned int type, - struct resource *res) -{ - struct resource *r, *prev = NULL; - int i; - - pci_bus_for_each_resource(bus, r, i) { - if (!r) - continue; - - if ((r->flags & IORESOURCE_TYPE_BITS) != type) - continue; - - /* If this resource is at or past the cursor, skip it */ - if (res) { - if (r == res) - continue; - if (r->end > res->end) - continue; - if (r->end == res->end && r->start > res->start) - continue; - } - - if (!prev) - prev = r; - - /* - * A small resource is higher than a large one that ends at - * the same address. - */ - if (r->end > prev->end || - (r->end == prev->end && r->start > prev->start)) - prev = r; - } - - return prev; -} - /** * pci_bus_alloc_resource - allocate a resource from a parent bus * @bus: PCI bus @@ -132,10 +89,9 @@ pci_bus_alloc_resource(struct pci_bus *bus, struct resource *res, resource_size_t), void *alignf_data) { - int ret = -ENOMEM; + int i, ret = -ENOMEM; struct resource *r; resource_size_t max = -1; - unsigned int type = res->flags & IORESOURCE_TYPE_BITS; type_mask |= IORESOURCE_IO | IORESOURCE_MEM; @@ -143,9 +99,10 @@ pci_bus_alloc_resource(struct pci_bus *bus, struct resource *res, if (!(res->flags & IORESOURCE_MEM_64)) max = PCIBIOS_MAX_MEM_32; - /* Look for space at highest addresses first */ - r = pci_bus_find_resource_prev(bus, type, NULL); - for ( ; r; r = pci_bus_find_resource_prev(bus, type, r)) { + pci_bus_for_each_resource(bus, r, i) { + if (!r) + continue; + /* type_mask must match */ if ((res->flags ^ r->flags) & type_mask) continue; -- cgit v1.1 From c0f5ac5426f7fd82b23dd5c6a1e633b290294a08 Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Thu, 16 Dec 2010 10:38:41 -0700 Subject: Revert "resources: support allocating space within a region from the top down" This reverts commit e7f8567db9a7f6b3151b0b275e245c1cef0d9c70. Acked-by: H. Peter Anvin Signed-off-by: Bjorn Helgaas Signed-off-by: Jesse Barnes --- Documentation/kernel-parameters.txt | 5 -- include/linux/ioport.h | 1 - kernel/resource.c | 98 ++----------------------------------- 3 files changed, 4 insertions(+), 100 deletions(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index cdd2a6e..8b61c93 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2175,11 +2175,6 @@ and is between 256 and 4096 characters. It is defined in the file reset_devices [KNL] Force drivers to reset the underlying device during initialization. - resource_alloc_from_bottom - Allocate new resources from the beginning of available - space, not the end. If you need to use this, please - report a bug. - resume= [SWSUSP] Specify the partition device for software suspend diff --git a/include/linux/ioport.h b/include/linux/ioport.h index d377ea8..b227902 100644 --- a/include/linux/ioport.h +++ b/include/linux/ioport.h @@ -112,7 +112,6 @@ struct resource_list { /* PC/ISA/whatever - the normal PC address spaces: IO and memory */ extern struct resource ioport_resource; extern struct resource iomem_resource; -extern int resource_alloc_from_bottom; extern struct resource *request_resource_conflict(struct resource *root, struct resource *new); extern int request_resource(struct resource *root, struct resource *new); diff --git a/kernel/resource.c b/kernel/resource.c index 9fad33e..560659f 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -40,23 +40,6 @@ EXPORT_SYMBOL(iomem_resource); static DEFINE_RWLOCK(resource_lock); -/* - * By default, we allocate free space bottom-up. The architecture can request - * top-down by clearing this flag. The user can override the architecture's - * choice with the "resource_alloc_from_bottom" kernel boot option, but that - * should only be a debugging tool. - */ -int resource_alloc_from_bottom = 1; - -static __init int setup_alloc_from_bottom(char *s) -{ - printk(KERN_INFO - "resource: allocating from bottom-up; please report a bug\n"); - resource_alloc_from_bottom = 1; - return 0; -} -early_param("resource_alloc_from_bottom", setup_alloc_from_bottom); - static void *r_next(struct seq_file *m, void *v, loff_t *pos) { struct resource *p = v; @@ -397,74 +380,7 @@ static bool resource_contains(struct resource *res1, struct resource *res2) } /* - * Find the resource before "child" in the sibling list of "root" children. - */ -static struct resource *find_sibling_prev(struct resource *root, struct resource *child) -{ - struct resource *this; - - for (this = root->child; this; this = this->sibling) - if (this->sibling == child) - return this; - - return NULL; -} - -/* - * Find empty slot in the resource tree given range and alignment. - * This version allocates from the end of the root resource first. - */ -static int find_resource_from_top(struct resource *root, struct resource *new, - resource_size_t size, resource_size_t min, - resource_size_t max, resource_size_t align, - resource_size_t (*alignf)(void *, - const struct resource *, - resource_size_t, - resource_size_t), - void *alignf_data) -{ - struct resource *this; - struct resource tmp, avail, alloc; - - tmp.start = root->end; - tmp.end = root->end; - - this = find_sibling_prev(root, NULL); - for (;;) { - if (this) { - if (this->end < root->end) - tmp.start = this->end + 1; - } else - tmp.start = root->start; - - resource_clip(&tmp, min, max); - - /* Check for overflow after ALIGN() */ - avail = *new; - avail.start = ALIGN(tmp.start, align); - avail.end = tmp.end; - if (avail.start >= tmp.start) { - alloc.start = alignf(alignf_data, &avail, size, align); - alloc.end = alloc.start + size - 1; - if (resource_contains(&avail, &alloc)) { - new->start = alloc.start; - new->end = alloc.end; - return 0; - } - } - - if (!this || this->start == root->start) - break; - - tmp.end = this->start - 1; - this = find_sibling_prev(root, this); - } - return -EBUSY; -} - -/* * Find empty slot in the resource tree given range and alignment. - * This version allocates from the beginning of the root resource first. */ static int find_resource(struct resource *root, struct resource *new, resource_size_t size, resource_size_t min, @@ -480,15 +396,14 @@ static int find_resource(struct resource *root, struct resource *new, tmp.start = root->start; /* - * Skip past an allocated resource that starts at 0, since the - * assignment of this->start - 1 to tmp->end below would cause an - * underflow. + * Skip past an allocated resource that starts at 0, since the assignment + * of this->start - 1 to tmp->end below would cause an underflow. */ if (this && this->start == 0) { tmp.start = this->end + 1; this = this->sibling; } - for (;;) { + for(;;) { if (this) tmp.end = this->start - 1; else @@ -509,10 +424,8 @@ static int find_resource(struct resource *root, struct resource *new, return 0; } } - if (!this) break; - tmp.start = this->end + 1; this = this->sibling; } @@ -545,10 +458,7 @@ int allocate_resource(struct resource *root, struct resource *new, alignf = simple_align_resource; write_lock(&resource_lock); - if (resource_alloc_from_bottom) - err = find_resource(root, new, size, min, max, align, alignf, alignf_data); - else - err = find_resource_from_top(root, new, size, min, max, align, alignf, alignf_data); + err = find_resource(root, new, size, min, max, align, alignf, alignf_data); if (err >= 0 && __request_resource(root, new)) err = -EBUSY; write_unlock(&resource_lock); -- cgit v1.1 From fcb119183c73bf0781009713f303e28b1fb13d3e Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Thu, 16 Dec 2010 10:38:46 -0700 Subject: resources: add arch hook for preventing allocation in reserved areas This adds arch_remove_reservations(), which an arch can implement if it needs to protect part of the address space from allocation. Sometimes that can be done by just putting a region in the resource tree, but there are cases where that doesn't work well. For example, x86 BIOS E820 reservations are not related to devices, so they may overlap part of, all of, or more than a device resource, so they may not end up at the correct spot in the resource tree. Acked-by: H. Peter Anvin Signed-off-by: Bjorn Helgaas Signed-off-by: Jesse Barnes --- include/linux/ioport.h | 1 + kernel/resource.c | 6 ++++++ 2 files changed, 7 insertions(+) diff --git a/include/linux/ioport.h b/include/linux/ioport.h index b227902..e9bb22c 100644 --- a/include/linux/ioport.h +++ b/include/linux/ioport.h @@ -123,6 +123,7 @@ extern void reserve_region_with_split(struct resource *root, extern struct resource *insert_resource_conflict(struct resource *parent, struct resource *new); extern int insert_resource(struct resource *parent, struct resource *new); extern void insert_resource_expand_to_fit(struct resource *root, struct resource *new); +extern void arch_remove_reservations(struct resource *avail); extern int allocate_resource(struct resource *root, struct resource *new, resource_size_t size, resource_size_t min, resource_size_t max, resource_size_t align, diff --git a/kernel/resource.c b/kernel/resource.c index 560659f..798e2fa 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -357,6 +357,10 @@ int __weak page_is_ram(unsigned long pfn) return walk_system_ram_range(pfn, 1, NULL, __is_ram) == 1; } +void __weak arch_remove_reservations(struct resource *avail) +{ +} + static resource_size_t simple_align_resource(void *data, const struct resource *avail, resource_size_t size, @@ -394,6 +398,7 @@ static int find_resource(struct resource *root, struct resource *new, struct resource *this = root->child; struct resource tmp = *new, avail, alloc; + tmp.flags = new->flags; tmp.start = root->start; /* * Skip past an allocated resource that starts at 0, since the assignment @@ -410,6 +415,7 @@ static int find_resource(struct resource *root, struct resource *new, tmp.end = root->end; resource_clip(&tmp, min, max); + arch_remove_reservations(&tmp); /* Check for overflow after ALIGN() */ avail = *new; -- cgit v1.1 From 30919b0bf356a8ee0ef4f7d38ca8ad99b96820b2 Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Thu, 16 Dec 2010 10:38:51 -0700 Subject: x86: avoid low BIOS area when allocating address space This implements arch_remove_reservations() so allocate_resource() can avoid any arch-specific reserved areas. This currently just avoids the BIOS area (the first 1MB), but could be used for E820 reserved areas if that turns out to be necessary. We previously avoided this area in pcibios_align_resource(). This patch moves the test from that PCI-specific path to a generic path, so *all* resource allocations will avoid this area. Acked-by: H. Peter Anvin Signed-off-by: Bjorn Helgaas Signed-off-by: Jesse Barnes --- arch/x86/kernel/Makefile | 1 + arch/x86/kernel/resource.c | 11 +++++++++++ arch/x86/pci/i386.c | 3 --- 3 files changed, 12 insertions(+), 3 deletions(-) create mode 100644 arch/x86/kernel/resource.c diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 9e13763..1e99475 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -45,6 +45,7 @@ obj-y += pci-dma.o quirks.o i8237.o topology.o kdebugfs.o obj-y += alternative.o i8253.o pci-nommu.o hw_breakpoint.o obj-y += tsc.o io_delay.o rtc.o obj-y += pci-iommu_table.o +obj-y += resource.o obj-$(CONFIG_X86_TRAMPOLINE) += trampoline.o obj-y += process.o diff --git a/arch/x86/kernel/resource.c b/arch/x86/kernel/resource.c new file mode 100644 index 0000000..407a900 --- /dev/null +++ b/arch/x86/kernel/resource.c @@ -0,0 +1,11 @@ +#include +#include + +void arch_remove_reservations(struct resource *avail) +{ + /* Trim out BIOS area (low 1MB) */ + if (avail->flags & IORESOURCE_MEM) { + if (avail->start < BIOS_END) + avail->start = BIOS_END; + } +} diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c index 8379c2c..b1805b7 100644 --- a/arch/x86/pci/i386.c +++ b/arch/x86/pci/i386.c @@ -72,9 +72,6 @@ pcibios_align_resource(void *data, const struct resource *res, return start; if (start & 0x300) start = (start + 0x3ff) & ~0x3ff; - } else if (res->flags & IORESOURCE_MEM) { - if (start < BIOS_END) - start = BIOS_END; } return start; } -- cgit v1.1 From 4dc2287c1805e7fe8a7cb90bbcd44abee8cdb914 Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Thu, 16 Dec 2010 10:38:56 -0700 Subject: x86: avoid E820 regions when allocating address space When we allocate address space, e.g., to assign it to a PCI device, don't allocate anything mentioned in the BIOS E820 memory map. On recent machines (2008 and newer), we assign PCI resources from the windows described by the ACPI PCI host bridge _CRS. On many Dell machines, these windows overlap some E820 reserved areas, e.g., BIOS-e820: 00000000bfe4dc00 - 00000000c0000000 (reserved) pci_root PNP0A03:00: host bridge window [mem 0xbff00000-0xdfffffff] If we put devices at 0xbff00000, they don't work, probably because that's really RAM, not I/O memory. This patch prevents that by removing the 0xbfe4dc00-0xbfffffff area from the "available" resource. I'm not very happy with this solution because Windows solves the problem differently (it seems to ignore E820 reserved areas and it allocates top-down instead of bottom-up; details at comment 45 of the bugzilla below). That means we're vulnerable to BIOS defects that Windows would not trip over. For example, if BIOS described a device in ACPI but didn't mention it in E820, Windows would work fine but Linux would fail. Reference: https://bugzilla.kernel.org/show_bug.cgi?id=16228 Acked-by: H. Peter Anvin Signed-off-by: Bjorn Helgaas Signed-off-by: Jesse Barnes --- arch/x86/kernel/resource.c | 38 +++++++++++++++++++++++++++++++++++++- 1 file changed, 37 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/resource.c b/arch/x86/kernel/resource.c index 407a900..89638af 100644 --- a/arch/x86/kernel/resource.c +++ b/arch/x86/kernel/resource.c @@ -1,11 +1,47 @@ #include #include +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 e820entry *entry; + + for (i = 0; i < e820.nr_map; i++) { + entry = &e820.map[i]; + + resource_clip(avail, entry->addr, + entry->addr + entry->size - 1); + } +} + void arch_remove_reservations(struct resource *avail) { - /* Trim out BIOS area (low 1MB) */ + /* Trim out BIOS area (low 1MB) and E820 regions */ if (avail->flags & IORESOURCE_MEM) { if (avail->start < BIOS_END) avail->start = BIOS_END; + + remove_e820_regions(avail); } } -- cgit v1.1 From a2c606d53ab71dee6410f10ef0adf67321d60e06 Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Thu, 16 Dec 2010 10:39:02 -0700 Subject: x86: avoid high BIOS area when allocating address space This prevents allocation of the last 2MB before 4GB. The experiment described here shows Windows 7 ignoring the last 1MB: https://bugzilla.kernel.org/show_bug.cgi?id=23542#c27 This patch ignores the top 2MB instead of just 1MB because H. Peter Anvin says "There will be ROM at the top of the 32-bit address space; it's a fact of the architecture, and on at least older systems it was common to have a shadow 1 MiB below." Acked-by: H. Peter Anvin Signed-off-by: Bjorn Helgaas Signed-off-by: Jesse Barnes --- arch/x86/include/asm/e820.h | 3 +++ arch/x86/kernel/resource.c | 3 ++- 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/e820.h b/arch/x86/include/asm/e820.h index 5be1542..e99d55d 100644 --- a/arch/x86/include/asm/e820.h +++ b/arch/x86/include/asm/e820.h @@ -72,6 +72,9 @@ struct e820map { #define BIOS_BEGIN 0x000a0000 #define BIOS_END 0x00100000 +#define BIOS_ROM_BASE 0xffe00000 +#define BIOS_ROM_END 0xffffffff + #ifdef __KERNEL__ /* see comment in arch/x86/kernel/e820.c */ extern struct e820map e820; diff --git a/arch/x86/kernel/resource.c b/arch/x86/kernel/resource.c index 89638af..2a26819 100644 --- a/arch/x86/kernel/resource.c +++ b/arch/x86/kernel/resource.c @@ -37,10 +37,11 @@ static void remove_e820_regions(struct resource *avail) void arch_remove_reservations(struct resource *avail) { - /* Trim out BIOS area (low 1MB) and E820 regions */ + /* Trim out BIOS areas (low 1MB and high 2MB) and E820 regions */ if (avail->flags & IORESOURCE_MEM) { if (avail->start < BIOS_END) avail->start = BIOS_END; + resource_clip(avail, BIOS_ROM_BASE, BIOS_ROM_END); remove_e820_regions(avail); } -- cgit v1.1