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    SubjectRe: ultrastor.c is a bit-rot
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    On Mon, 2008-03-17 at 16:59 +0200, Boaz Harrosh wrote:
    > Inspecting ultrastor.c it is clear to me that this was never used for
    > a loooooooooong time. Not since a PC has more then 2^24 bit of memory.
    > Let me explain below.
    >
    > Now I'm not saying it should be fixed. I'm saying that it should be dumped
    > in the account that it is not used by any one and that it does not work.
    >
    > Why it never worked?
    > ~~~~~~~~~~~~~~~~~~~~~
    >
    > The driver's header says it supports 3 cards
    >
    > * 14F - ISA first-party DMA HA with floppy support and WD1003 emulation.
    > * 24F - EISA Bus Master HA with floppy support and WD1003 emulation.
    > * 34F - VL-Bus Bus Master HA with floppy support (no WD1003 emulation).
    >
    > But Kconfig only specifies ISA. I'm not sure what a VL-Bus is.

    VL is vesa local ... it was an ISA like graphics bus that was fast and
    could reach > 16MB.

    > now the driver defines a static array of structures like this:
    >
    > struct {
    > ...
    >
    > struct mscp mscp[ULTRASTOR_MAX_CMDS];
    > } config = {0};
    >
    > and allocates a struct mscp in .queuecommand like this:
    > my_mscp = &config.mscp[mscp_index];
    >
    > it will go on preparing this my_mscp structure including stuffing
    > some mapped pointers. Lets put that aside for now.
    > At the very end it will pass this my_mscp structure to the card's
    > firmware like this:
    >
    > /* Store pointer in OGM address bytes */
    > outl(isa_virt_to_bus(my_mscp), config.ogm_address);
    >
    > Now this is one hell of a smart ISA card. But putting this aside.
    >
    > if the machine has more then 2^24 of memory. Then this will never
    > work, right? or I'm missing it completely?

    It will definitely work for EISA and VL bus. I think if you analyse the
    placement of kernel data segments for compiled in drivers, it might also
    work for ISA too, since I think the pfn will be low enough. It should
    fail as a module not just because the area will be out of range for ISA,
    but also because the module data segment is in vmalloc space, so the
    virt_to_bus assumptions of contiguity could be violated.

    James




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