IBM's Boot Manager and INT 13h extensions - OS2

This is a discussion on IBM's Boot Manager and INT 13h extensions - OS2 ; IA> BM uses Int13 or Int13X depending if there has been an 'I13X' IA> written to the master disk MBR that will get passed to BM. False. IBM's Boot Manager uses the INT 13h extensions if _whatever has invoked Boot ...

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Thread: IBM's Boot Manager and INT 13h extensions

  1. IBM's Boot Manager and INT 13h extensions

    IA> BM uses Int13 or Int13X depending if there has been an 'I13X'
    IA> written to the master disk MBR that will get passed to BM.

    False. IBM's Boot Manager uses the INT 13h extensions if _whatever has
    invoked Boot Manager_ has written an "I13X" flag _to a specific location in
    memory_ before doing so. So the primary MBR (which is usually what invokes
    Boot Manager) has to be written to set this flag.

    It's a very silly scheme.

    IA> BM only shows what it can 'scan' at the time. There are
    IA> no permanent 'entries' stored in the BM partition.

    Also false. IBM's Boot Manager contains the extended partition table entries
    for the four primary partitions. (The extended partition table entries for
    the remaining partitions are in the secondary MBRs for those partitions,
    however.)

  2. Re: IBM's Boot Manager and INT 13h extensions

    On Sun, 25 Jan 2004 09:13:52 UTC, Jonathan de Boyne Pollard
    wrote:

    > IA> BM uses Int13 or Int13X depending if there has been an 'I13X'
    > IA> written to the master disk MBR that will get passed to BM.
    >
    > False. IBM's Boot Manager uses the INT 13h extensions if _whatever has
    > invoked Boot Manager_ has written an "I13X" flag _to a specific location in
    > memory_ before doing so. So the primary MBR (which is usually what invokes
    > Boot Manager) has to be written to set this flag.
    >
    > It's a very silly scheme.


    Well, it isn't false if you only consider the default type of install.
    Anyone capable of getting LILO programmed to include the 'I13X' to pass
    to the BM probably does not need the advise that the BM can 'break'
    access to partitions over 1024 cylinders if they damage the MBR etc, and
    they should even be capable of getting it to boot OS/2 above 1024
    directly. I did read recently that GRUB provided access 'out of the
    box' while LILO needed a particular setting for it to switch to that
    address mode. Wether that makes a difference for BM I don't know as I
    can't remember testing that setup. I'll leave it for someone else to
    test how a GRUB -> BM works, as even Vpart that is supposed to be using
    'I13X' in memory (eCS above 1024 boots from it normally ever since the
    first BETA,) was tested to start BM after it and that BM would not show
    my systems that were above 1024 cylinders. The memory location for
    'I13X' should be the same I would think, no? Same thing for all the
    other managers like Power boot and Boot Magic that I tried. In theory,
    you should be correct, but is there a practical example of it working
    that way? I've not seen any mention of it...


    > IA> BM only shows what it can 'scan' at the time. There are
    > IA> no permanent 'entries' stored in the BM partition.
    >
    > Also false. IBM's Boot Manager contains the extended partition table entries
    > for the four primary partitions. (The extended partition table entries for
    > the remaining partitions are in the secondary MBRs for those partitions,
    > however.)


    Which in the case of systems above 1024 discussed here still means they
    are 'scanned' to produce them on the menu. Isn't this data you mention
    stored in the MBR partition table not the Boot Manager anyway? Boot
    Manager is a separate place, not in MBR as others might be, right? For
    example, you can change your disk that is used as 'master' in your BIOS,
    so that you use a different Boot Manager on another disk, and it shows
    the same disk data as far as I remember, as long as it can 'read' the
    tables. I could have misremembered what Jan van-Wijk said, but I'm
    fairly sure he told me not to expect to find the data in the Boot
    Manager...

    BTW; Not seen much of you since our ILink days...Are you getting a feed
    into FIDO to see this or what?

    Iain...



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