• Heiko Carstens's avatar
    s390/ipl: revert Load Normal semantics for LPAR CCW-type re-IPL · ead1dec8
    Heiko Carstens authored
    This reverts the two commits
    
    7afbeb6d ("s390/ipl: always use load normal for CCW-type re-IPL")
    0f7451ff ("s390/ipl: use load normal for LPAR re-ipl")
    
    The two commits did not take into account that behavior of standby
    memory changes fundamentally if the re-IPL method is changed from
    Load Clear to Load Normal.
    
    In case of the old re-IPL clear method all memory that was initially
    in standby state will be put into standby state again within the
    re-IPL process. Or in other words: memory that was brought online
    before a re-IPL will be offline again after a reboot.
    
    Given that we use different re-IPL methods depending on the hypervisor
    and CCW-type vs SCSI re-IPL it is not easy to tell in advance when and
    why memory will stay online or will be offline after a re-IPL.
    This does also have other side effects, since memory that is online
    from the beginning will be in ZONE_NORMAL by default vs ZONE_MOVABLE
    for memory that is offline.
    
    Therefore, before the change, a user could online and offline memory
    easily since standby memory was always in ZONE_NORMAL.  After the
    change, and a re-IPL, this depended on which memory parts were online
    before the re-IPL.
    
    From a usability point of view the current behavior is more than
    suboptimal. Therefore revert these changes until we have a better
    solution and get back to a consistent behavior. The bad thing about
    this is that the time required for a re-IPL will be significantly
    increased for configurations with several 100GB or 1TB of memory.
    Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
    Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
    ead1dec8
ipl.c 51.9 KB