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Differential D3986

Update mips busdma to handle unmapped/out-of-context buffers
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Authored by linimon on Oct 22 2015, 9:13 PM.
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jmallett
imp
adrian
jah
Summary

Use pmap_quick* functions in mips busdma, for bounce buffers and cache maintenance. This makes it safe to sync buffers that have no VA mapping associated with the busdma map, but may have other mappings, possibly on different CPUs. This also makes it safe to sync unmapped bounce buffers in non-sleepable thread contexts.

Similar to r286787 for x86, this treats userspace buffers the same as unmapped buffers and no longer borrows the UVA for sync operations.

While here, stop trying to use uncacheable memory for bounce buffers. It seems likely that the slowness of uncached copies would overwhelm the extra overhead of cache maintenance on the bounce buffers. If uncached memory does end up being needed here for some reason, kmem_alloc_contig(...VM_MEMATTR_UNCACHEABLE) should be used instead.

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rS FreeBSD src repository - subversion
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Event Timeline

jah updated this revision to Diff 9641.Oct 22 2015, 9:13 PM
jah retitled this revision from to Update mips busdma to handle unmapped/out-of-context buffers.
jah updated this object.
jah edited the test plan for this revision. (Show Details)
Herald added a subscriber: imp. · View Herald TranscriptOct 22 2015, 9:13 PM
jah added a reviewer: adrian.Oct 22 2015, 9:14 PM
adrian added reviewers: imp, jmallett.Oct 22 2015, 9:22 PM
jah updated this revision to Diff 9653.Oct 23 2015, 12:08 PM

Remove unclear comments on PHYS_TO_VM_PAGE().
Noted by: avg

adrian edited edge metadata.Oct 26 2015, 11:59 AM

Can you test this out via a qemu-system-mips (from qemu-devel) package?

https://github.com/freebsd/freebsd-wifi-build/wiki/MipsQemuEmulatorImages

jah added a comment.Oct 28 2015, 4:00 AM
In D3986#83554, @adrian wrote:

Can you test this out via a qemu-system-mips (from qemu-devel) package?

https://github.com/freebsd/freebsd-wifi-build/wiki/MipsQemuEmulatorImages

I have a stock MALTA64 (big endian) kernel booting under qemu...disk I/O seems to work fine. I'm building a mips32 image now.
Are there any workloads I should throw at it?

adrian added a comment.Oct 28 2015, 4:29 AM

Just build some software or something that'll churn the VM and do disk IO. :)

jah added a comment.Oct 28 2015, 10:21 PM
In D3986#83956, @adrian wrote:

Just build some software or something that'll churn the VM and do disk IO. :)

I ended up just putting both the mips64 and mips32 VMs through buildworld. Everything seems to be fine.

adrian added a comment.Oct 28 2015, 10:24 PM

ok, I'll try this out on some mips32 hardware and see what happens.

Does unmapped IO work with USB storage?

sbruno added a subscriber: sbruno.Sep 16 2016, 4:49 PM
linimon commandeered this revision.Dec 25 2023, 11:22 PM
linimon added a reviewer: jah.
linimon added a subscriber: linimon.

Note that this DR is OBE.

linimon abandoned this revision.Dec 25 2023, 11:22 PM

MIPS support is OBE.

sbruno removed a subscriber: sbruno.Dec 26 2023, 5:36 PM

Revision Contents
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sys/
mips/
mips/
163 lines

Diff 9653

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sys/mips/mips/busdma_machdep.c

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