LinuxKPI: Add dma_length field to struct scatterlist
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Authored by wulf on Sun, Sep 13, 9:01 AM.

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bz
emaste
dumbbell

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linuxkpi

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rGa6b40d746b4b: LinuxKPI: Add dma_length field to struct scatterlist

Summary

On Linux dma_length field of struct scatterlist is present on the
arches where DMA mapping code is able to coalesce adjacent segments
of physical address space. It contains total length of coalesced
segments while length field contains non-coalesced length of each
segment. On other arches dma_length is aliased to length field with
sg_dma_len macro. As FreeBSD does not merge scatterlist segments it
do not have dma_length field. It is appered that at least i915kms
driver depends on existence of dma_length field.

Add the field and disable it by default. To enable add to Makefile

.if ${MACHINE_CPUARCH} == "i386" || ${MACHINE_CPUARCH} == "amd64" || \\

${MACHINE_CPUARCH} == "aarch64" || ${MACHINE_CPUARCH} == "powerpc"

CFLAGS+= -DCONFIG_NEED_SG_DMA_LENGTH
.endif

Reported by: Ryan Fahy
GHI: https://github.com/freebsd/drm-kmod/issues/315

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rG FreeBSD src repository

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Buildable 76820
Build 73703: arc lint + arc unit

Event Timeline

wulf created this revision.Sun, Sep 13, 9:01 AM

Herald added subscribers: linuxkpi, emaste, imp. · View Herald TranscriptSun, Sep 13, 9:01 AM

wulf requested review of this revision.Sun, Sep 13, 9:01 AM

Harbormaster completed remote builds in B76820: Diff 186565.Sun, Sep 13, 9:01 AM

wulf added reviewers: linuxkpi, bz, emaste.Sun, Sep 13, 9:03 AM

Otherwise I think I am fine with this.

sys/compat/linuxkpi/common/include/linux/scatterlist.h
522	Am I reading it right that this is the single change of the function compared to the previous? Can we keep one copy of the rest of the logic factoring it out with a bool argument to pick one or the other length?