diff options
Diffstat (limited to 'gpxe/src/arch/i386/core/etherboot.prefix.lds')
| -rw-r--r-- | gpxe/src/arch/i386/core/etherboot.prefix.lds | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/gpxe/src/arch/i386/core/etherboot.prefix.lds b/gpxe/src/arch/i386/core/etherboot.prefix.lds new file mode 100644 index 00000000..3550a2a3 --- /dev/null +++ b/gpxe/src/arch/i386/core/etherboot.prefix.lds @@ -0,0 +1,100 @@ +OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386") +OUTPUT_ARCH(i386) + +ENTRY(_prefix_start) +SECTIONS { + /* Prefix */ + .prefix : { + _verbatim_start = . ; + _prefix_start = . ; + *(.prefix) + . = ALIGN(16); + _prefix_end = . ; + } = 0x9090 + _prefix_size = _prefix_end - _prefix_start; + + .text.nocompress : { + *(.prefix.udata) + } = 0x9090 + + decompress_to = . ; + .prefix.zdata : { + _compressed = . ; + *(.prefix.zdata) + _compressed_end = . ; + } + _compressed_size = _compressed_end - _compressed; + + . = ALIGN(16); + _verbatim_end = . ; + + + /* Size of the core of etherboot in memory */ + _base_size = _end - _text; + + /* _prefix_size is the length of the non-core etherboot prefix */ + _prefix_size = _prefix_end - _prefix_start; + + /* _verbatim_size is the actual amount that has to be copied to base memory */ + _verbatim_size = _verbatim_end - _verbatim_start; + + /* _image_size is the amount of base memory needed to run */ + _image_size = _base_size + _prefix_size; + + /* Standard sizes rounded up to paragraphs */ + _prefix_size_pgh = (_prefix_size + 15) / 16; + _verbatim_size_pgh = (_verbatim_size + 15) / 16; + _image_size_pgh = (_image_size + 15) / 16 ; + + /* Standard sizes in sectors */ + _prefix_size_sct = (_prefix_size + 511) / 512; + _verbatim_size_sct = (_verbatim_size + 511) / 512; + _image_size_sct = (_image_size + 511) / 512; + + /* Symbol offsets and sizes for the exe prefix */ + _exe_hdr_size = 32; + _exe_size = _verbatim_size; /* Should this be - 32 to exclude the header? */ + _exe_size_tail = (_exe_size) % 512; + _exe_size_pages = ((_exe_size) + 511) / 512; + _exe_bss_size = ((_image_size - _verbatim_size) + 15) / 16; + _exe_ss_offset = (_stack_offset + _prefix_size - _exe_hdr_size + 15) / 16 ; + + /* This is where we copy the compressed image before decompression. + * Prepare to decompress in place. The end mark is about 8.25 bytes long, + * and the worst case symbol is about 16.5 bytes long. Therefore + * We need to reserve at least 25 bytes of slack here. + * Currently I reserve 2048 bytes of just slack to be safe :) + * 2048 bytes easily falls within the BSS (the defualt stack is 4096 bytes) + * so we really are decompressing in place. + * + * Hmm. I missed a trick. In the very worst case (no compression) + * the encoded data is 9/8 the size as it started out so to be completely + * safe I need to be 1/8 of the uncompressed code size past the end. + * This will still fit compfortably into our bss in any conceivable scenario. + */ + _compressed_copy = _edata + _prefix_size - _compressed_size + + /* The amount to overflow _edata */ + MAX( ((_edata - _text + 7) / 8) , 2016 ) + 32; + _assert = ASSERT( ( _compressed_copy - _prefix_size ) < _ebss , "Cannot decompress in place" ) ; + + decompress = DEFINED(decompress) ? decompress : 0; + /DISCARD/ : { + *(.comment) + *(.note) + } + + /* Symbols used by the prefixes whose addresses are inconvinient + * to compute, at runtime in the code. + */ + image_basemem_size = DEFINED(image_basemem_size)? image_basemem_size : 65536; + image_basemem = DEFINED(image_basemem)? image_basemem : 65536; + _prefix_real_to_prot = _real_to_prot + _prefix_size ; + _prefix_prot_to_real = _prot_to_real + _prefix_size ; + _prefix_image_basemem_size = image_basemem_size + _prefix_size ; + _prefix_image_basemem = image_basemem + _prefix_size ; + _prefix_rm_in_call = _rm_in_call + _prefix_size ; + _prefix_in_call = _in_call + _prefix_size ; + _prefix_rom = rom + _prefix_size ; + _prefix_rm_etherboot_location = rm_etherboot_location + _prefix_size ; + _prefix_stack_end = _stack_end + _prefix_size ; +} |