Date: Wed, 28 Jan 2009 08:15:31 -0600 (CST) From: Mark Tinguely <tinguely@casselton.net> To: arm@freebsd.org, gjb@semihalf.com, tinguely@casselton.net Subject: Re: svn commit: r186730 - in head... Message-ID: <200901281415.n0SEFVsG075471@casselton.net> In-Reply-To: <4980356A.4090403@semihalf.com>
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> I downloaded your patch and applied it (after a few modification to get rid of compile errors). However, when I boot the board with new code it hangs. The problem is with uma allocator for pv_entries. When there is no more entries available it create new ones. It includes mapping memory into kernel using pmap_qenter. And then recurrence starts, pmap_qenter calls pmap_kenter which tries to allocate pv_entry and so on. > I think that pv_entries for pmap_kenter should be allocated from some special pool to avoid this problem. Or some threshold could be set for uma allocator to force allocation of new pv_entries if number of free entries drops below the threshold, but I am not sure if it is possible without extending uma interface. > > Grzesiek Thank-you for the feedback. I should have anticipated that. If mapping the kernel mappings is the correct thing to do, we may add a map/virtual address entry to the md_page to remember the first mapping and then only manage on the duplicate kernel mapping. The extra check should be less overhead than managing every kernel mapping. --Mark Tinguely
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