On 2 March 2015 at 15:05, K. Macy <km...@freebsd.org> wrote: > On Mon, Mar 2, 2015 at 12:42 PM, Adrian Chadd <adr...@freebsd.org> wrote: >> Hi, >> >> gonzo@ committed a fix (r278615) to the videocore driver for the >> raspberry pi. The fix involved doing an explicit wire of pages that >> were about to be passed down to the hardware to send to the >> videobuffer hardware. >> >> It turns out that doing vm_fault_quick_hold_pages() wasn't enough - >> the pages weren't being wired, and they may disappear before the >> hardware gets to them. > > > Then your code is buggy or you've hit a bug in the VM. Holding a page > is a short-term wiring.
Well, you can look at what's going on in the vchiq code. gonzo made it an explicit wire in order to avoid issues. > Right above vm_page_hold(): > /* > * Keep page from being freed by the page daemon > * much of the same effect as wiring, except much lower > * overhead and should be used only for *very* temporary > * holding ("wiring"). > */ What's the definition of "very temporary holding" ? What's the behavioural difference? -adrian _______________________________________________ email@example.com mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"