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Michael Brown
887d77c27a
[pcbios] Inhibit INT 15 memory map hiding on brain-dead BIOSes
Some really moronic BIOSes bring up the PXE stack via the UNDI loader entry point during POST, and then don't bother to unload it before overwriting the code and data segments. If this happens, we really don't want to leave INT 15 hooked, because that will cause any loaded OS to die horribly as soon as it attempts to fetch the system memory map. We use a heuristic to detect whether or not we are being loaded at the top of free base memory. If we determine that we are being loaded at some other arbitrary location in base memory, then we assume that it's not safe to hook INT 15.
gPXE README File gPXE is an implementation of the PXE specification for network booting, with extensions to allow additional features such as booting via HTTP, iSCSI, and AoE. In generally, gPXE is compatible with the industry-standard PXE specification, and also supports Etherboot .nbi file loading and some additional protocols and features. For more detailed information about gPXE, please visit our project website at: http://etherboot.org/ BUILDING gPXE IMAGE FROM SOURCE If you don't want to install development tools, and have access to the Web, you can get gPXE and Etherboot ROM images made on demand from http://rom-o-matic.net/ If you would like to compile gPXE images from source, here are some tips. We normally compile gPXE images on x86, 32-bit Linux machines. It is possible to also use x86-64 machines. We use gcc compiler options to create 32-bit output. It is important to have the necessary software packages installed. A gcc-based toolchain is required. The following packages (at least) are required: - a gcc tool chain (gcc 3.x or gcc 4.x) - binutils - perl - syslinux - mtools To test your environment, cd to the "src" directory and type: make You should see a lot of output, and when it stops, the "bin" directory should be populated with gPXE images and object files. To learn more about what to build and how to use gPXE, please visit our project website at http://etherboot.org/ , particularly the "howto" section. CONTACTING US Pointers to our project mailing lists are on http://etherboot.org/ Real-time help is often available on IRC on the #etherboot channel of irc.freenode.net.
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