From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3BF4A68B.5080803@embeddededge.com> Date: Fri, 16 Nov 2001 00:39:23 -0500 From: Dan Malek MIME-Version: 1.0 To: Steve Rossi Cc: Embedded Linux PPC List Subject: Re: mmap & no cache regions References: <3BF1939A.B96072AC@labs.mot.com> Content-Type: text/plain; charset=us-ascii; format=flowed Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: Steve Rossi wrote: > .....I learned that consistent_alloc is not sufficent to > guarantee cache coherency on the mmaped region Well, it has no clue about what you are doing. It's purpose is to ensure the kernel's mapping of that page is set properly. > .... - in fact I had to mark > these pages PAGE_NO_CACHE in the user space application's memory map as > well. Yep, that's because the kernel and applications have their own page tables and page attributes. > .....- but is it safe > to assume that the application's memory map will be destroyed so I don't > have to worry about marking the pages in that map as cacheable again? I was about to write a couple of pages when it is best to answer this with a simple "yes." When the application releases this space, the page tables are simply destroyed. The kernel does it's weird attribute change because it doesn't really "release" the page as an application does. That's all I'll say for now :-). Thanks. -- Dan ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/