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    SubjectRe: Why SCSI module needed for PCI-IDE ATA only disks ?
    Robert Hancock wrote:
    > Ed Sweetman wrote:
    >> Jeff Garzik wrote:
    >>> Bernard Pidoux wrote:
    >>>> I am asking why need to compile the following modules while I do not
    >>>> have any SCSI device ?
    >>> libata uses SCSI to provide a lot of infrastructure that it would
    >>> otherwise have to recreate. Also, using SCSI meant that it
    >>> automatically worked in existing installers.
    >>> Jeff
    >> This confusion could easily be remedied by explaining the requirement
    >> in the Help output for libata drivers/section. Also, making a
    >> dependency in the menu (since there is one) or automatically
    >> selecting the required scsi items when you select a libata driver
    >> would seem logical. As it is, nothing is said of scsi requirements in
    >> menuconfig. Trying to boot a machine without compiling the scsi
    >> drivers (something you're allowed to do) results in a system that
    >> boots and initializes the ata busses but can't communicate to any of
    >> the drives on them, (useless).
    > You can't select libata drivers without the SCSI core. However, you
    > can select libata drivers without the SCSI disk (sd) or the SCSI CD
    > (sr) drivers. However, that's a legitimate configuration as you may
    > have only hard disks, only CD drives, etc. and there would be no need
    > to build the other module. This isn't a major problem for most
    > standard configurations as those drivers are needed to handle things
    > like USB and FireWire flash drives, external HDs/optical drives, etc.
    > anyway.
    What's not a legitimate configuration is libata drivers, no low level
    scsi drivers, no ide drivers and no sd,sr,sg drivers. Yet, that is the
    configuration the kernel currently gives you. How is that more correct
    than any of the 3 solutions I have suggested?

    The point is there is nothing in the help section in libata to tell you
    that these "scsi" drivers are needed for disk / cdrom / generic device
    access in libata. Indeed, there is no obvious connection to the two.

    Either configuration options need to be put in the libata directory that
    would just select the drivers (libata disk, cdrom, generic configuration
    options which would just enable the appropriate config variable, in
    other words in the menu config have two config directives which would
    enable the same drivers but be under different submenus to avoid
    confusion), or a short description in the help dialog to tell users that
    they have to enable those scsi drivers under the scsi section to use
    their drivers under the libata section.

    It's not safe to assume people will have those drivers compiled because
    of usb or firewire or flash drives. Assuming that situation is 10 times
    more problematic than any possible argument against just selecting those
    scsi drivers automatically and letting the user deselect them as needed
    when they select a libata driver.

    Personaly, I prefer a help dialog blurb explaining that the user has to
    enable certain scsi drivers to actually use their libata driven
    devices. That, at the very least, I believe is necessary and not
    asking much.

    I've made patches before that impliment these trivial features in
    menuconfig. In the grand scheme of things this isn't that important to
    kernel development, but it's going to get more and more feedback as more
    people move to libata and eventually it will be fixed in some manner
    similar to those i've mentioned, I think it would just be better to do
    it now than wait until the mailing list is filled with end users asking
    why they need scsi when they obviously only have sata/ide and want to
    use libata.
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      Last update: 2006-12-06 03:11    [W:0.044 / U:3.352 seconds]
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