From mboxrd@z Thu Jan 1 00:00:00 1970 From: Grant Grundler Date: Tue, 04 May 2004 17:19:58 +0000 Subject: Re: mmap() of /dev/kmem issue Message-Id: <20040504171958.GF1701@cup.hp.com> List-Id: References: <4097C51D.71EA0BEA@email.mot.com> In-Reply-To: <4097C51D.71EA0BEA@email.mot.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org On Tue, May 04, 2004 at 11:30:21AM -0500, Mario Smarduch wrote: > I have problem of viewing memory contents via mmap() of /dev/kmem. 1) which regions/addresses are you accessing? 2) what values do you see/should see? 3) test case? grant > After mmap()'ing /dev/kmem for reading > it appears that data accessed in the kernel lives in > different cache lines from data accessed in the user space. > The lseek()/read() from kernel reflects latest updates, > but same reads from user space mmap fetches old data, and > vice versa when updating from user. When I flush the > caches (cat of a big file to another file), then user mapped > value reflects the latest changes but then again remains > frozen. I'm having trouble understanding how can this > happen since the caches are physically indexed. > Any ideas what the problem could be? > > - Mario. > > - > To unsubscribe from this list: send the line "unsubscribe linux-ia64" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html