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    SubjectRe: OpenGL-based framebuffer concepts
    On 6/1/06, D. Hazelton <> wrote:
    > > > 5) The system needs to be robust. Daemons can be killed by the OOM
    > > > mechanism, you don't want to lose your console in the middle of trying
    > > > to fix a problem. This also means that you have to be able to display
    > > > printk's from inside interrupt handles.
    > Point of disagreement. Tons of userspace helpers isn't a good choice.

    Where do you get 'tons'? There will probably be one for initial reset,
    one for VESA based mode setting and a few more if there is device
    specific code needed for a specific card.

    Making console rely on a permanent daemon that is subject to getting
    killed by the OOM mechanism is not a workable solution.

    You also need to think about how cursors are handled. A non-root app
    needs to be able to move the cursor. Actually moving the cursor
    requires root. The in-kernel console system needs a cursor. It would
    be much better if cursor control was implemented in the device

    > I don't know about doing a printk from inside interrupt context - the current
    > architecture doesn't, IIRC, support printk from inside interrupt context for
    > certain drivers for various reasons.

    Printk works from inside interrupt handlers currently. This is an
    absolute requirement for kernel debugging that can't be removed.
    Because of this requirement there has to be a way for all drivers to
    draw the console entirely inside the kernel. You can not make calls to
    user space from inside interrupt handlers.

    > > > 6) Things like panics should be visible no matter what is running. No
    > > > more silent deaths.

    Panics can occur inside interrupt handlers. You can't queue up printks
    in this context and they display them later, the kernel just died,
    there is no later.

    Jon Smirl
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      Last update: 2006-06-01 22:37    [W:0.043 / U:4.348 seconds]
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