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    SubjectRe: [RFC] [PATCH] virtual memmap on sparsemem v3 [1/4] map and unmap
    On Fri, 8 Dec 2006 16:01:42 +0900
    KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:

    > When we want to map pages into the kernel space by vmalloc()'s routine,
    > we always need 'struct page' to do that.
    >
    > There are cases where there is no page struct to use (bootstrap, etc..).
    > This function is designed to help map any memory to anywhere, anytime.
    >
    > Users should manage their virtual/physical space by themselves.
    > Because it's complex and danger to manage virtual address space by
    > each function's own code, it's better to use fixed address.
    >
    > Note: My first purpose is supporting virtual mem_map both at boot/hotplug
    > sharing the same logic.
    >

    A little thing:


    > + if (ops->k_pte_alloc) {
    > + ret = ops->k_pte_alloc(pmd, addr, data);
    > + if (ret)
    > + return ret;
    > + } else {
    > + pte = pte_alloc_kernel(pmd, addr);
    > + if (!pte)
    > + return -ENOMEM;
    > + }

    > + if (ops->k_pmd_alloc) {
    > + ret = ops->k_pmd_alloc(pud, addr, data);
    > + if (ret)
    > + return ret;
    > + } else {
    > + pmd = pmd_alloc(&init_mm, pud, addr);
    > + if (!pmd)
    > + return -ENOMEM;

    > + if (ops->k_pud_alloc) {
    > + ret = ops->k_pud_alloc(pgd, addr, data);
    > + if (ret)
    > + return ret;
    > + } else {
    > + pud = pud_alloc(&init_mm, pgd, addr);
    > + if (!pud)
    > + return -ENOMEM;
    > + }

    Generally we prefer to simply *require* that the function vector be filled
    in appropriately. So if the caller has no special needs, the caller will
    set their gen_map_kern_ops.k_pte_alloc to point at pte_alloc_kernel().

    erk, pte_alloc_kernel() is a macro. As is pmd_alloc(), etc. Well, let
    that be a lesson to us. What a mess.

    I suppose we could go through and convert them all to inlines and then the
    compiler will generate an out-of-line copy for us. Better would be to turn
    these things into regular, out-of-line C functions.

    What a mess.
    -
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