Fellow hackers, I'm trying to mod my laptop hardware configuration to support > 3 Gb RAM. I'm quite convinced it can support up to 3.7 Gb. Here's how I'm doing it. 1. Increase TOLUD (highest DRAM address for mem controller to decode) register on i945PM chipset. Currently, it's C0000000. 2. Remap GeForce's PCI_BASE_ADDRESS_1 (frame buffer) from 0xc0000000 - 0xd0000000 to 0xe0000000 - 0xf0000000. 3. Change the PCIX bridge's prefetchable memory range (base, limit registers) to match Geforce's frame buffer. 4. Remap PCIX extended configuration space MMIO space from 0xe0000000 - 0xf0000000 to 0xf0000000 - 0xf4000000 (done by writing i945 register) 5. Override the BIOS e820 memory map. Initially, I just used the memmap= boot arguments. Later I hard coded a new map into grub2's grub_machine_mmap_iterate(). grub2 by default overrides the BIOS's int15, e820 with this new map. Here's my old physical memory map: BIOS-provided physical RAM map: BIOS-e820: 0000000000000000 - 000000000009f800 (usable) BIOS-e820: 000000000009f800 - 00000000000a0000 (reserved) BIOS-e820: 00000000000dc000 - 00000000000e4000 (reserved) BIOS-e820: 00000000000e8000 - 0000000000100000 (reserved) BIOS-e820: 0000000000100000 - 00000000bfee0000 (usable) BIOS-e820: 00000000bfee0000 - 00000000bff00000 (ACPI NVS) BIOS-e820: 00000000bff00000 - 00000000c0000000 (reserved) BIOS-e820: 00000000e0000000 - 00000000f0000000 (reserved) PCIX extended config space BIOS-e820: 00000000fec00000 - 00000000fec10000 (reserved) BIOS-e820: 00000000fed00000 - 00000000fed00400 (reserved) BIOS-e820: 00000000fed14000 - 00000000fed1a000 (reserved) MCH bar registers BIOS-e820: 00000000fed1c000 - 00000000fed90000 (reserved) BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved) BIOS-e820: 00000000ff000000 - 0000000100000000 (reserved) (all other PCI devices - NICs, USB, etc use ~16MB MMIO space around 0xd0000000) new memory map: [e0000000, f0000000) changes to [f0000000, f4000000) only Step 1 requires moding the BIOS, which I'll have to wait on until I learn how to flash a bricked BIOS. I've done steps 2 to 5 and it frees 256Mb of address space as expected. On Debian, lspci reports the GeForce's frame buffer is mapped at 0xe0000000 and graphics works correctly. When I try to boot Vista, I get a BSOD 0.5s after the logo screen saying the BIOS is not ACPI compliant. are my guesses: 1. Grub didn't hook int15, e820 - I'm not sure if this is done for chainloader boots. I guess I can test this by doing a chainloader boot for Linux and executing int15, e820. 2. PCI BIOS reports inconsistent results from my changes (assuming Windows uses it) 3. ACPI tables contain inconsistent data (e.g. PCIX extended configuration base). I will be very disappointed if I have to modify the PCI BIOS or ACPI tables. Does anyone know what could be wrong? Thanks Yale -- 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
