netfront: purge page flipping support
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Authored by liuw_liuw.name on Oct 14 2015, 2:41 PM.

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Currently neither Linux nor FreeBSD netback supports page flipping. NetBSD still supports that. It is not sure how many people actually use page flipping, but page flipping is supposed to be slower than copying nowadays. It will also shatter frontend / backend address space.

Overall this feature is more of a burden than a benefit.

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rS FreeBSD src repository - subversion

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liuw_liuw.name updated this revision to Diff 9374.Oct 14 2015, 2:41 PM

liuw_liuw.name retitled this revision from to netfront: purge page flipping support.

liuw_liuw.name updated this object.

liuw_liuw.name edited the test plan for this revision. (Show Details)

liuw_liuw.name added reviewers: royger, network.

liuw_liuw.name set the repository for this revision to rS FreeBSD src repository - subversion.

liuw_liuw.name added a project: network.

Herald added a subscriber: imp. · View Herald TranscriptOct 14 2015, 2:41 PM

liuw_liuw.name added a child revision: D3893: netfront: shrink MAX_TX_REQ_FRAGS by one.Oct 14 2015, 2:50 PM

liuw_liuw.name removed a child revision: D3893: netfront: shrink MAX_TX_REQ_FRAGS by one.

LGTM, only some minor comments that I can amend (if you agree) while committing if you don't want to sent a new version.

sys/dev/xen/netfront/netfront.c
1245	Not your fault, but this message is extremely unhelpful.
1761	I would join this with the previous if, so it's if (error =! 0 \|\| feature_rx_copy == 0) return (EPROTONOSUPPORT);