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Differential D37082 Diff 112089 sys/x86/x86/busdma_bounce.c

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sys/x86/x86/busdma_bounce.c

Show First 20 Lines • Show All 317 Lines • ▼ Show 20 Lines if ((dmat->bounce_flags & BUS_DMA_COULD_BOUNCE) != 0) {
* basis up to a sane limit. * basis up to a sane limit.
*/ */
if (dmat->common.alignment > 1) if (dmat->common.alignment > 1)
maxpages = MAX_BPAGES; maxpages = MAX_BPAGES;
else else
maxpages = MIN(MAX_BPAGES, Maxmem - maxpages = MIN(MAX_BPAGES, Maxmem -
atop(dmat->common.lowaddr)); atop(dmat->common.lowaddr));
if ((dmat->bounce_flags & BUS_DMA_MIN_ALLOC_COMP) == 0 || if ((dmat->bounce_flags & BUS_DMA_MIN_ALLOC_COMP) == 0 ||
(bz->map_count > 0 && bz->total_bpages < maxpages)) { (bz->map_count > 0 && bz->total_bpages < maxpages)) {
jhbUnsubmitted
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The final check here (bz->total_pages < maxpages) does keep us from adding pages for future maps once we do hit MAX_BPAGES. But I still find it rather convoluted.

jhb: The final check here (`bz->total_pages < maxpages`) does keep us from adding pages for future…
cpercivaAuthorUnsubmitted
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Not if BUS_DMA_MIN_ALLOC_COMP isn't set. Which I think means we add one extra page per tag (not per dmamap as I said earlier).

As before, I really can't say I understand why the code was designed this way...

cperciva: Not if BUS_DMA_MIN_ALLOC_COMP isn't set. Which I think means we add one extra page per tag…
pages = MAX(atop(dmat->common.maxsize), 1); pages = MAX(atop(dmat->common.maxsize), 1);
pages = MIN(dmat->common.nsegments, pages);
pages = MIN(maxpages - bz->total_bpages, pages); pages = MIN(maxpages - bz->total_bpages, pages);
pages = MAX(pages, 1); pages = MAX(pages, 1);
if (alloc_bounce_pages(dmat, pages) < pages) if (alloc_bounce_pages(dmat, pages) < pages)
error = ENOMEM; error = ENOMEM;
if ((dmat->bounce_flags & BUS_DMA_MIN_ALLOC_COMP) if ((dmat->bounce_flags & BUS_DMA_MIN_ALLOC_COMP)
== 0) { == 0) {
if (error == 0) { if (error == 0) {
dmat->bounce_flags |= dmat->bounce_flags |=
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