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    SubjectRe: IDE + SMP Lockup (no OOPS) in 2.2.12, 2.2.10
    Theodore Y. Ts'o wrote:
    > Date: Fri, 1 Oct 1999 20:19:34 +0100 (BST)
    > From: Alan Cox <>
    > Because the IDE layer disables the shared IRQ in question for periods of
    > time of you dont have hdparm -u set, and for some periods of time anyway.
    > Basically its the IDE code being obnoxious. Fixing the IDE locking would
    > improve this, but would be a real pain because older IDE controllers you
    > want to disable_irq and stuff to avoid nasty performance problems.
    > Actually, it's worse than that. On some older IDE controllers not
    > turning off interrupts will cause data corruption on the disk. Read the
    > hdparm man page about the -u option..... If it were only performance
    > problems, given that it screws over the serial driver, we could make the
    > argument to change the default. But given that on some trashy hardware
    > it causes data loss, it's harder to make that argument.... or I would
    > have made it a long time ago. (hdparm -u should be in the serial HOWTO
    > and a number of FAQ's, though!)

    Ok, sure, of course. I know that. However as 99% of the users won't be
    reading enough manuals to do the hdparm -u1, it is still neccesary to
    find out why the 128-byte-fifo-uart is losing characters, while the
    standard 16-byte-fifo-uart isn't.

    Turns out the trigger level on the new UART was set at 112. That's 16
    before the end. Reducing the trigger level 32, fixed a lot, but still
    I was able to overrun the new uart at 19k2, while I couldn't overflow
    the 16550 at 115k2.


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