Date: Sun, 26 Jul 1998 15:29:15 -0700 From: David Greenman <dg@root.com> To: zhihuizhang <bf20761@binghamton.edu> Cc: hackers <freebsd-hackers@FreeBSD.ORG> Subject: Re: APTDpde question (pmap) Message-ID: <199807262229.PAA16544@implode.root.com> In-Reply-To: Your message of "Sun, 26 Jul 1998 16:27:43 EDT." <Pine.SOL.L3.93.980726155752.23464A-100000@bingsun2>
next in thread | previous in thread | raw e-mail | index | archive | help
>In pmap.c module, we set PTDPTDI entry of the page directory page to point >to itself. So PTDpde and PTmap works well. However, I do not find a >similar setting of APTDTDI (=1023) in pmap.c. My question is how APTDpde >and the alternate address space it's supposed to relate to (APTmap) are >used. (has something to do with pmap copy?) The alternate page table map is used when the kernel wants to access the page tables of a non-current process. The page directory of the target process is mapped at PTD offset 1023, which causes the target process's page tables to become accessable in the final 4MB of the current address space. -DG David Greenman Co-founder/Principal Architect, The FreeBSD Project To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199807262229.PAA16544>