From a1e9778203b15b86bc2219e87478d3be9acce735 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Sat, 16 Apr 2005 15:25:12 -0700 Subject: [PATCH] [PATCH] x86_64: Port over e820 gap detection from i386 Look for gaps in the e820 memory map to put PCI resources in. This hopefully fixes problems with the PCI code assigning 32bit BARs MMIO resources which are >32bit. Signed-off-by: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/x86_64/kernel/e820.c | 59 ++++++++++++++++++++++++++++++++++++++ arch/x86_64/kernel/setup.c | 12 +------- include/asm-x86_64/e820.h | 1 + 3 files changed, 61 insertions(+), 11 deletions(-) diff --git a/arch/x86_64/kernel/e820.c b/arch/x86_64/kernel/e820.c index 657003e461..56516ac92e 100644 --- a/arch/x86_64/kernel/e820.c +++ b/arch/x86_64/kernel/e820.c @@ -511,3 +511,62 @@ void __init parse_memopt(char *p, char **from) end_user_pfn >>= PAGE_SHIFT; } +unsigned long pci_mem_start = 0xaeedbabe; + +/* + * Search for the biggest gap in the low 32 bits of the e820 + * memory space. We pass this space to PCI to assign MMIO resources + * for hotplug or unconfigured devices in. + * Hopefully the BIOS let enough space left. + */ +__init void e820_setup_gap(void) +{ + unsigned long gapstart, gapsize; + unsigned long last; + int i; + int found = 0; + + last = 0x100000000ull; + gapstart = 0x10000000; + gapsize = 0x400000; + i = e820.nr_map; + while (--i >= 0) { + unsigned long long start = e820.map[i].addr; + unsigned long long end = start + e820.map[i].size; + + /* + * Since "last" is at most 4GB, we know we'll + * fit in 32 bits if this condition is true + */ + if (last > end) { + unsigned long gap = last - end; + + if (gap > gapsize) { + gapsize = gap; + gapstart = end; + found = 1; + } + } + if (start < last) + last = start; + } + + if (!found) { + gapstart = (end_pfn << PAGE_SHIFT) + 1024*1024; + printk(KERN_ERR "PCI: Warning: Cannot find a gap in the 32bit address range\n" + KERN_ERR "PCI: Unassigned devices with 32bit resource registers may break!\n"); + } + + /* + * Start allocating dynamic PCI memory a bit into the gap, + * aligned up to the nearest megabyte. + * + * Question: should we try to pad it up a bit (do something + * like " + (gapsize >> 3)" in there too?). We now have the + * technology. + */ + pci_mem_start = (gapstart + 0xfffff) & ~0xfffff; + + printk(KERN_INFO "Allocating PCI resources starting at %lx (gap: %lx:%lx)\n", + pci_mem_start, gapstart, gapsize); +} diff --git a/arch/x86_64/kernel/setup.c b/arch/x86_64/kernel/setup.c index b06221e319..57f619052b 100644 --- a/arch/x86_64/kernel/setup.c +++ b/arch/x86_64/kernel/setup.c @@ -76,9 +76,6 @@ int __initdata acpi_force = 0; int acpi_numa __initdata; -/* For PCI or other memory-mapped resources */ -unsigned long pci_mem_start = 0x10000000; - /* Boot loader ID as an integer, for the benefit of proc_dointvec */ int bootloader_type; @@ -495,7 +492,6 @@ static void __init reserve_ebda_region(void) void __init setup_arch(char **cmdline_p) { - unsigned long low_mem_size; unsigned long kernel_end; ROOT_DEV = old_decode_dev(ORIG_ROOT_DEV); @@ -654,13 +650,7 @@ void __init setup_arch(char **cmdline_p) request_resource(&ioport_resource, &standard_io_resources[i]); } - /* Will likely break when you have unassigned resources with more - than 4GB memory and bridges that don't support more than 4GB. - Doing it properly would require to use pci_alloc_consistent - in this case. */ - low_mem_size = ((end_pfn << PAGE_SHIFT) + 0xfffff) & ~0xfffff; - if (low_mem_size > pci_mem_start) - pci_mem_start = low_mem_size; + e820_setup_gap(); #ifdef CONFIG_GART_IOMMU iommu_hole_init(); diff --git a/include/asm-x86_64/e820.h b/include/asm-x86_64/e820.h index 5b376e42b1..08f83a4b4f 100644 --- a/include/asm-x86_64/e820.h +++ b/include/asm-x86_64/e820.h @@ -50,6 +50,7 @@ extern void e820_print_map(char *who); extern int e820_mapped(unsigned long start, unsigned long end, unsigned type); extern void e820_bootmem_free(pg_data_t *pgdat, unsigned long start,unsigned long end); +extern void e820_setup_gap(void); extern void __init parse_memopt(char *p, char **end); -- 2.39.5