The combination of HIGHMEM64G and PCI doesn't work in 2.6.31-rc1, causing a hang in PCI initialisation during boot: Linux version 2.6.31-rc1 (mikpe@brewer) (gcc version 4.3.4 20090621 (prerelease) (GCC) ) #1 Fri Jun 26 16:01:50 CEST 2009 KERNEL supported cpus: Intel GenuineIntel BIOS-provided physical RAM map: BIOS-e820: 0000000000000000 - 000000000009ec00 (usable) BIOS-e820: 000000000009ec00 - 00000000000a0000 (reserved) BIOS-e820: 00000000000e4000 - 0000000000100000 (reserved) BIOS-e820: 0000000000100000 - 000000007ff90000 (usable) BIOS-e820: 000000007ff90000 - 000000007ff9e000 (ACPI data) BIOS-e820: 000000007ff9e000 - 000000007ffe0000 (ACPI NVS) BIOS-e820: 000000007ffe0000 - 0000000080000000 (reserved) BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved) BIOS-e820: 00000000ffb00000 - 0000000100000000 (reserved) BIOS-e820: 0000000100000000 - 0000000200000000 (usable) DMI 2.4 present. last_pfn = 0x200000 max_arch_pfn = 0x1000000 init_memory_mapping: 0000000000000000-00000000379fe000 NX (Execute Disable) protection: active RAMDISK: 37ebb000 - 37fef7c6 Allocated new RAMDISK: 00221000 - 003557c6 Move RAMDISK from 0000000037ebb000 - 0000000037fef7c5 to 00221000 - 003557c5 7302MB HIGHMEM available. 889MB LOWMEM available. mapped low ram: 0 - 379fe000 low ram: 0 - 379fe000 node 0 low ram: 00000000 - 379fe000 node 0 bootmap 00009000 - 0000ff40 (7 early reservations) ==> bootmem [0000000000 - 00379fe000] #0 [0000000000 - 0000001000] BIOS data page ==> [0000000000 - 0000001000] #1 [0000100000 - 000021cf18] TEXT DATA BSS ==> [0000100000 - 000021cf18] #2 [000009ec00 - 0000100000] BIOS reserved ==> [000009ec00 - 0000100000] #3 [000021d000 - 000022022c] BRK ==> [000021d000 - 000022022c] #4 [0000007000 - 0000009000] PGTABLE ==> [0000007000 - 0000009000] #5 [0000221000 - 00003557c6] NEW RAMDISK ==> [0000221000 - 00003557c6] #6 [0000009000 - 0000010000] BOOTMAP ==> [0000009000 - 0000010000] Zone PFN ranges: DMA 0x00000000 -> 0x00001000 Normal 0x00001000 -> 0x000379fe HighMem 0x000379fe -> 0x00200000 Movable zone start PFN for each node early_node_map[3] active PFN ranges 0: 0x00000000 -> 0x0000009e 0: 0x00000100 -> 0x0007ff90 0: 0x00100000 -> 0x00200000 Allocating PCI resources starting at 80000000 (gap: 80000000:7ee00000) Built 1 zonelists in Zone order, mobility grouping on. Total pages: 1556269 Kernel command line: ro root=LABEL=32/ console=ttyS0,115200 PID hash table entries: 4096 (order: 12, 16384 bytes) Dentry cache hash table entries: 131072 (order: 7, 524288 bytes) Inode-cache hash table entries: 65536 (order: 6, 262144 bytes) Enabling fast FPU save and restore... done. Enabling unmasked SIMD FPU exception support... done. Initializing CPU#0 Initializing HighMem for node 0 (000379fe:00200000) Memory: 6220996k/8388608k available (691k kernel code, 68768k reserved, 203k data, 144k init, 5379656k highmem) virtual kernel memory layout: fixmap : 0xfffe6000 - 0xfffff000 ( 100 kB) pkmap : 0xffa00000 - 0xffc00000 (2048 kB) vmalloc : 0xf81fe000 - 0xff9fe000 ( 120 MB) lowmem : 0xc0000000 - 0xf79fe000 ( 889 MB) .init : 0xc01e2000 - 0xc0206000 ( 144 kB) .data : 0xc01acd86 - 0xc01dfbdc ( 203 kB) .text : 0xc0100000 - 0xc01acd86 ( 691 kB) Checking if this processor honours the WP bit even in supervisor mode...Ok. NR_IRQS:16 Fast TSC calibration using PIT Detected 2400.277 MHz processor. Console: colour VGA+ 80x25 console [ttyS0] enabled Calibrating delay loop (skipped), value calculated using timer frequency.. 4800.55 BogoMIPS (lpj=24002770) Mount-cache hash table entries: 512 CPU: L1 I cache: 32K, L1 D cache: 32K CPU: L2 cache: 4096K using mwait in idle threads. CPU: Intel(R) Core(TM)2 CPU 6600 @ 2.40GHz stepping 06 Checking 'hlt' instruction... OK. PCI: PCI BIOS revision 3.00 entry at 0xf0031, last bus=2 PCI: Using configuration type 1 for base access PCI: Probing PCI hardware pci 0000:00:01.0: PME# supported from D0 D3hot D3cold pci 0000:00:01.0: PME# disabled pci 0000:00:1a.7: PME# supported from D0 D3hot D3cold pci 0000:00:1a.7: PME# disabled pci 0000:00:1b.0: PME# supported from D0 D3hot D3cold pci 0000:00:1b.0: PME# disabled pci 0000:00:1d.7: PME# supported from D0 D3hot D3cold pci 0000:00:1d.7: PME# disabled pci 0000:00:1f.0: quirk: region 0800-087f claimed by ICH6 ACPI/GPIO/TCO pci 0000:00:1f.0: quirk: region 0480-04bf claimed by ICH6 GPIO pci 0000:00:1f.0: ICH7 LPC Generic IO decode 1 PIO at 0294 (mask 0003) pci 0000:00:1f.2: PME# supported from D3hot pci 0000:00:1f.2: PME# disabled pci 0000:02:02.0: PME# supported from D1 D2 D3hot D3cold pci 0000:02:02.0: PME# disabled pci 0000:00:1e.0: transparent bridge pci 0000:00:1f.0: PIIX/ICH IRQ router [8086:2810] At this point the kernel hangs hard until rebooted. Rebooting with mem=2048M (to avoid issues with mappings >= 4GB) allows PCI init to proceed and print: pci 0000:00:01.0: PCI bridge, secondary bus 0000:01 pci 0000:00:01.0: IO window: 0x9000-0xbfff pci 0000:00:01.0: MEM window: 0xff800000-0xff8fffff pci 0000:00:01.0: PREFETCH window: 0x000000bff00000-0x000000dfefffff pci 0000:00:1e.0: PCI bridge, secondary bus 0000:02 pci 0000:00:1e.0: IO window: 0xc000-0xcfff pci 0000:00:1e.0: MEM window: 0xff900000-0xff9fffff pci 0000:00:1e.0: PREFETCH window: disabled pci 0000:00:01.0: found PCI INT A -> IRQ 11 pci 0000:00:01.0: sharing IRQ 11 with 0000:00:1a.0 pci 0000:00:01.0: sharing IRQ 11 with 0000:01:00.0 Unpacking initramfs... Freeing initrd memory: 1233k freed platform rtc_cmos: registered platform RTC device (no PNP device found) Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A Platform driver 'serial8250' needs updating - please use dev_pm_ops Freeing unused kernel memory: 144k freed Red Hat nash version 5.1.19.0.3 starting ... Booting with pci=off also allows the kernel to boot. Reconfiguring with NOHIGHMEM or HIGHMEM4G also allows the kernel to boot. This is a regression from 2.6.30 and earlier kernels. /Mikael -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html