Date: Sun, 05 Oct 2014 13:15:12 +0900 (JST) From: Kohji Okuno <okuno.kohji@jp.panasonic.com> To: kostikbel@gmail.com Cc: stable@freebsd.org, freebsd-current@freebsd.org, okuno.kohji@jp.panasonic.com Subject: Re: About pmap_mapdev() & pmap_unmapdev() Message-ID: <20141005.131512.606074419488263735.okuno.kohji@jp.panasonic.com> In-Reply-To: <20141004155803.GQ26076@kib.kiev.ua> References: <20141004092030.GP26076@kib.kiev.ua> <20141004.205335.1782700760623869892.okuno.kohji@jp.panasonic.com> <20141004155803.GQ26076@kib.kiev.ua>
next in thread | previous in thread | raw e-mail | index | archive | help
Hi, > On Sat, Oct 04, 2014 at 08:53:35PM +0900, Kohji Okuno wrote: >> Hi Konstantin, >> >> Thank you for your prompt response. >> I will test and report from next monday. >> >> >> In addtion, I have one question. >> >> In current and 10-stable, is vm_map_delete() called by kva_free()? >> > No, kva_free() only releases the vmem backing, leaving the page >> > tables intact. This is why I only did the stable/9 patch. >> >> Where are PTEs allocated by pmap_mapdev() freed in current and 10-stable? >> Could you please explain me? > They are not freed. The removal of the vmem which covers the address > space managed by corresponding ptes, allows the reuse of both KVA region > and corresponding PTEs in the tables. The only concern with the resident > page tables is to avoid two kva_alloc() to step over each other, and > this is ensured by vmem. I agree that normal pages are reusable. But, since the pages mapped by pmap_mapdev() are concerned with the physicall address of device (For example: video memory), these PTEs aren't reusable, I think. So, should we free these PTEs by pmap_unmapdev()? Best regards, Kohji Okuno
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20141005.131512.606074419488263735.okuno.kohji>