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| author | Michael Brown | 2007-01-13 02:48:12 +0100 |
|---|---|---|
| committer | Michael Brown | 2007-01-13 02:48:12 +0100 |
| commit | 86171c53f4515dda266825e92b54a1d1e31228e4 (patch) | |
| tree | 4173f86c5155f99850b26df041d9ba272d7390af /src | |
| parent | Add HTTP test support (diff) | |
| download | ipxe-86171c53f4515dda266825e92b54a1d1e31228e4.tar.gz ipxe-86171c53f4515dda266825e92b54a1d1e31228e4.tar.xz ipxe-86171c53f4515dda266825e92b54a1d1e31228e4.zip | |
Damn Broadcom and their damned incorrect assumptions about x86 memory
allocation.
Diffstat (limited to 'src')
| -rw-r--r-- | src/arch/i386/prefix/libprefix.S | 27 |
1 files changed, 24 insertions, 3 deletions
diff --git a/src/arch/i386/prefix/libprefix.S b/src/arch/i386/prefix/libprefix.S index 1c471aa03..d1da0b00d 100644 --- a/src/arch/i386/prefix/libprefix.S +++ b/src/arch/i386/prefix/libprefix.S @@ -17,6 +17,26 @@ * */ +/** + * High memory temporary load address + * + * Temporary buffer into which to copy (or decompress) our runtime + * image, prior to calling get_memmap() and relocate(). We don't + * actually leave anything here once install() has returned. + * + * We use the start of an even megabyte so that we don't have to worry + * about the current state of the A20 line. + * + * We use 4MB rather than 2MB because there is at least one commercial + * PXE ROM ("Broadcom UNDI, PXE-2.1 (build 082) v2.0.4") which stores + * data required by the UNDI ROM loader (yes, the ROM loader; that's + * the component which should be impossible to damage short of + * screwing with the MMU) around the 2MB mark. Sadly, this is not a + * joke. + * + */ +#define HIGHMEM_LOADPOINT ( 4 << 20 ) + #define CR0_PE 1 .arch i386 @@ -345,11 +365,12 @@ install_prealloc: movw %ax, (init_librm_vector+2) movw %ax, (prot_call_vector+2) - /* Install .text and .data to 2MB mark. Use 2MB to avoid - * problems with A20. + /* Install .text and .data to temporary area in high memory, + * prior to reading the E820 memory map and relocating + * properly. */ call flatten_real_mode - movl $(2<<20), %edi + movl $HIGHMEM_LOADPOINT, %edi call install_highmem /* Set up initial protected-mode GDT, call relocate(). |