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  1. Core ReactOS
  2. CORE-15427

FAT16 bootloader needs rework

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    • Task
    • Resolution: Unresolved
    • Major
    • None
    • Bootloader
    • None

    Description

      Our freeldr.sys file became somewhat large and doesn't fit in current memory layout used in fat.bin VBR.

      FAT16 boot sequence looks like this: MBR -> VBR/BPB (fat.bin) -> code at first 512 bytes of freeldr.sys (which is jumped over in other VBRs) -> main freeldr.sys code

      And here we have an issue with that "second part" of VBR code: it loads whole FAT into memory at 7000:0000 which leaves us 395264 bytes for freeldr.sys (we load it at 0000:F800). Currently freeldr.sys file can be 366592 bytes (gcc-built) or 448512 bytes (msvc-built). Obviously, msvc-compiled version doesn't fit into space and thus boot is being failed.

      Possible solution - do not load whole FAT into memory and only read it from disk where we need. But this would affect floppy-disk performance, which should be addressed somehow

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          is duplicated by

          Bug - A problem which impairs or prevents the functions of the product. CORE-13740 A halt at the beginning of the 2nd stage (FAT16 partition)

          • Major - Major loss of function.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. CORE-14558 Invalid instruction causes a crash at the boot to the second stage of install

          • Major - Major loss of function.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. CORE-16195 Can`t boot from partition 500Mb on Disk 20Gb

          • Major - Major loss of function.
          • Resolved
          relates to

          Bug - A problem which impairs or prevents the functions of the product. CORE-15384 Corruption when writing to FAT16 volumes

          • Major - Major loss of function.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. CORE-16864 FreeLdr assert OptionalHeader->SizeOfImage > MAX_FREELDR_PE_SIZE

          • Major - Major loss of function.
          • Resolved

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              hbelusca hbelusca
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              Dates

                Created:
                Updated: