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57e700f4f4
Linuxbios boots an Opteron motherboard with 1GB memory. Linuxbios directly loads a recent linux kernel. The memory layout is like this: BIOS-provided physical RAM map: BIOS-e820: 0000000000000000 - 0000000000000e18 (reserved) BIOS-e820: 0000000000000e18 - 00000000000a0000 (usable) BIOS-e820: 00000000000c0000 - 00000000000f0000 (usable) BIOS-e820: 00000000000f0000 - 00000000000f0400 (reserved) BIOS-e820: 00000000000f0400 - 0000000040000000 (usable) The f0000-f0400 region contains IRQ and ACPI tables. At some point the kernel builds a resource table containing all physical address ranges and type of hardware the addresses are mapped to. The table is accessible via /proc/iomem: # cat /proc/iomem 00000000-00000e17 : reserved 00000e18-0009ffff : System RAM 000a0000-000bffff : Video RAM area 000c0000-000cbfff : Video ROM 000f0000-000fffff : System ROM e0000000-efffffff : PCI Bus #03 e0000000-efffffff : 0000:03:00.0 f0000000-f3ffffff : GART f4000000-f60fffff : PCI Bus #03 f4000000-f4ffffff : 0000:03:00.0 f5000000-f5ffffff : 0000:03:00.0 f6000000-f601ffff : 0000:03:00.0 f6100000-f6100fff : 0000:00:01.0 f6101000-f6101fff : 0000:00:02.0 f6101000-f6101fff : ohci_hcd f6102000-f6102fff : 0000:00:04.0 f6103000-f6103fff : 0000:00:07.0 f6103000-f6103fff : sata_nv f6104000-f6104fff : 0000:00:08.0 f6104000-f6104fff : sata_nv f6105000-f6105fff : 0000:00:0a.0 f6106000-f61060ff : 0000:00:02.1 f6200000-f620ffff : 0000:40:01.0 As you can see, the 00000000000f0400-0000000040000000 region is not listed. It is not listed because the kernel unconditionally adds "000f0000-000fffff : System ROM" first (look for "request_resource(&iomem_resource, &system_rom_resource)"), and then the attempt to add f0400-40000000 range fails because of overlapping. The kernel does not care that the range is not listed there. Kexec does. It uses the /proc/iomem file to instruct the kexec system call how to place the segments of a new kernel in the physical memory. Kexec fails to start a new kernel because it cannot locate enough physical memory. This must be fixed either in linux or linuxbios. Assuming that linuxbios is to be fixed, I cooked a patch which provides this memory layout: BIOS-provided physical RAM map: BIOS-e820: 0000000000000000 - 0000000000000e18 (reserved) BIOS-e820: 0000000000000e18 - 00000000000a0000 (usable) BIOS-e820: 00000000000c0000 - 00000000000f0000 (usable) BIOS-e820: 00000000000f0000 - 0000000000100000 (reserved) BIOS-e820: 0000000000100000 - 0000000040000000 (usable) The /proc/iomem contains: # cat /proc/iomem 00000000-00000e17 : reserved 00000e18-0009ffff : System RAM 000a0000-000bffff : Video RAM area 000c0000-000cbfff : Video ROM 000f0000-000fffff : System ROM 00100000-3fffffff : System RAM 00100000-00203c61 : Kernel code 00203c62-00248c3f : Kernel data e0000000-efffffff : PCI Bus #03 e0000000-efffffff : 0000:03:00.0 f0000000-f3ffffff : GART f4000000-f60fffff : PCI Bus #03 f4000000-f4ffffff : 0000:03:00.0 f5000000-f5ffffff : 0000:03:00.0 f6000000-f601ffff : 0000:03:00.0 f6100000-f6100fff : 0000:00:01.0 f6101000-f6101fff : 0000:00:02.0 f6101000-f6101fff : ohci_hcd f6102000-f6102fff : 0000:00:04.0 f6103000-f6103fff : 0000:00:07.0 f6103000-f6103fff : sata_nv f6104000-f6104fff : 0000:00:08.0 f6104000-f6104fff : sata_nv f6105000-f6105fff : 0000:00:0a.0 f6106000-f61060ff : 0000:00:02.1 f6200000-f620ffff : 0000:40:01.0 Kexec is happier with the patch. Regards, Signed-off-by: Roman Kononov <kononov195-lbl@yahoo.com> Acked-by: Stefan Reinauer <stepan@coresystems.de> git-svn-id: svn://svn.coreboot.org/coreboot/trunk@2542 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1 |
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------------------------------------------------------------------------------- LinuxBIOS README ------------------------------------------------------------------------------- LinuxBIOS is a Free Software project aimed at replacing the proprietary BIOS you can find in most of today's computers. It performs just a little bit of hardware initialization and then executes one of many possible payloads, e.g. a Linux kernel. Payloads -------- After the basic initialization of the hardware has been performed, any desired "payload" can be started by LinuxBIOS. Examples include: * A Linux kernel * FILO (a simple bootloader with filesystem support) * OpenBIOS (a free IEEE1275-1994 Open Firmware implementation) * Etherboot (for network booting and booting from raw IDE or FILO) * ADLO (for booting Windows 2000 or OpenBSD) * Plan 9 (a distributed operating system) * memtest86 (for testing your RAM) Supported Hardware ------------------ LinuxBIOS supports a wide range of chipsets, devices, and mainboards. For details please consult: * http://www.linuxbios.org/Supported_Motherboards * http://www.linuxbios.org/Supported_Chipsets_and_Devices Website and Mailing List ------------------------ Further details on the project, a FAQ, many HOWTOs, news, development guidelines and more can be found on the LinuxBIOS website: http://www.linuxbios.org You can contact us directly on the LinuxBIOS mailing list: http://www.linuxbios.org/Mailinglist Copyright and License --------------------- The copyright on LinuxBIOS is owned by quite a large number of individual developers and companies. Please check the individual source files for details. LinuxBIOS is licensed under the terms of the GNU General Public License (GPL). Some files are licensed under the "GPL (version 2, or any later version)", and some files (mostly those derived from the Linux kernel) are licensed under the "GPL, version 2". For some parts, which were derived from other projects, other (GPL-compatible) licenses may apply. Please check the individual source files for details.