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    SubjectRe: One problem in reassign pci bus number?
    On Thu, May 03, 2012 at 08:15:29PM -0700, Yinghai Lu wrote:
    >>>
    >>>I updated for-pci-busn-alloc branch with updating of probe_resource()...
    >>>and removing bus->secondary and subordinate.
    >>>
    >> You mean you remove the bus->secondary field?
    >> So the pci_bus->number hold the bus number?
    >> I think this is a huge work.
    >>>Please check if you can understand it ...
    >>>
    >>>http://git.kernel.org/?p=linux/kernel/git/yinghai/linux-yinghai.git;a=commitdiff;h=7de8df57b223d54af95ffe67f8da2dd39a265971
    >> Some question:
    >>
    >> +static resource_size_t __find_res_top_free_size(struct resource *res,
    >> +                                                int skip_nr)
    >> +{
    >> +       resource_size_t n_size;
    >> +       struct resource tmp_res;
    >> +
    >> +       */
    >> +        *   find out free number below res->end that we can use.
    >> +        *      res->start to res->start + skip_nr - 1 can not be used.
    >> +        */
    >> +       n_size = resource_size(res);
    >> +       if (n_size <= skip_nr)
    >> +               return 0;
    >> +
    >> +       n_size -= skip_nr;
    >> +       memset(&tmp_res, 0, sizeof(struct resource));
    >> +       while (n_size > 0) {
    >> +               int ret;
    >> +
    >> +               ret = __allocate_resource(res, &tmp_res, n_size,
    >> +                       res->end - n_size + skip_nr, res->end,
    >> +                       1, NULL, NULL, false);
    >> +               if (ret == 0) {
    >> +                       __release_resource(&tmp_res);
    >> +                       break;
    >> +               }
    >> +               n_size--;
    >> +       }
    >> +
    >> +       return n_size;
    >> +}
    >> So this is trying to find out the biggest free space of res?
    >> On the right side?
    >>
    >> For example we have , res like
    >>   90-150
    >>        105-140
    >> The __find_res_top_free_size() will return 10 instead of 15.
    >> So this is the design decision to find the right side free resouce not
    >> the left side?
    >
    > __find_res_top_free_size() is called by probe_resource().
    >
    >probe_resource will return [91-104].
    Hmm... I think the result is returned by this while loop.
    + while (n_size >= needed_size) {
    + ret = allocate_resource(b_res, busn_res, n_size,
    + b_res->start + skip_nr, b_res->end,
    + 1, NULL, NULL);
    + if (!ret)
    + return ret;
    + n_size--;
    + }
    __find_res_top_free_size() is not called.

    BTW, even if this value is returned by __find_res_top_free_size(), or
    returned after this function is called, the purpose of the
    __find_res_top_free_size() is to get the biggest free space under the
    first parameter?
    >
    >Thanks
    >
    >Yinghai

    --
    Richard Yang
    Help you, Help me

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