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RE: [partman] Re: Error writing MBR or EMBR to disk. -solved-

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  • Antoine Leca
    ... Not sure it is that bogus. ... Perhaps it was, when the PC (-XT) was designed (was the central idea of G. Kidall in CP/M, for sure.) However, the
    Message 1 of 5 , Nov 6, 2007
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      dggerman12 wrote:
      > <unrelated_helpful_info>
      > RPM relies on BIOS services to write to the disk.
      >
      > With AMIBIOS,
      > If "virus protection" in the BIOS settings is enabled,
      > requests to write, VIA THE BIOS, to boot sectors
      > presents the pop up:
      >
      > BootSector Write !!
      > VIRUS: Continue (Y/N)?
      >
      > Several stand-alone utilities,
      > as well as linux fdisk, (apparently) access
      > the HD directly (i.e. not via BIOS)! (IMHO bogus!)

      Not sure it is that bogus.

      > All this time I thought the point of the BIOS was to
      > provide access to hardware, especially the HD.

      Perhaps it was, when the PC (-XT) was designed (was the central idea of
      G. Kidall in CP/M, for sure.)
      However, the performances you get using the BIOS are very poor,
      particularly when the OS is running in 32-bit mode (while the BIOS is
      16-bit, real-mode, based, thus incurring a overwhelming overhead to
      switch context.)
      Plus, when BIOS32 services became a tangible and viable reality (i.e.
      not buggy, not patent-encumbred, not royalties-encumbred), everybody and
      his dog had figured how to do it directly with better performances
      (thanks to the ATA standards), even Minix (!), so BIOS32 never actually
      succeed.

      As a result, BIOS still survives for a limited extend, mainly to be able
      to start the "real" OS (and even in this task, Intel/Microsoft have
      ideas to kill it, named EFI; but it is still unsuccessful, not the least
      reason being the amount of royalties AMD-based computer makers might
      have to pay Intel to use EFI...)

      > I didn't expect linux fdisk to bypass the BIOS.

      You cannot expect anything else! Linux is running in 32-bit mode, and
      its design certainly does not accept a random application such as
      'fdisk' to switch mode (stopping everything else on the computer) and
      run in real mode, just to access BIOS services. Even if it were for very
      good reasons like repartition.

      For the very same reason, RPM cannot run under NT: the NT kernel cannot
      afford to allow access to the BIOS services; that is the main difference
      with the Win9x kernel, which does accept that any application uses the
      BIOS while running (and give a chance to grab all resources; it is the
      main reason why less people use 9x these days ;-).)

      Another one is that this way, you can repartition your disk even if it
      is not supported by the BIOS, like if it is a RAID array, or simply
      SCSI.


      Antoine
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