Date: Sun, 28 Dec 2008 10:47:26 +1100 From: Peter Jeremy <peterjeremy@optushome.com.au> To: Gerry Weaver <gerryw@compvia.com> Cc: freebsd-hackers@freebsd.org Subject: Re: How to access kernel memory from user space Message-ID: <20081227234726.GC64280@server.vk2pj.dyndns.org> In-Reply-To: <20081224212207.4cc4874b@mail01.compvia.com> References: <20081224212207.4cc4874b@mail01.compvia.com>
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--4jXrM3lyYWu4nBt5 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2008-Dec-24 15:22:07 -0600, Gerry Weaver <gerryw@compvia.com> wrote: >to keep it minimal. Is there any significant trade off in performance >between the two approaches? No. In both cases, the actual access is managed through the normal hardware translation the same as any other data. About the only difference is that the kmem approach will probably involve an additional page of mapping because your data structure probably won't be page-aligned by default. > Also, Is there anything in the source or ports tree that I could >use as an example for the device node case? I presume you've been looking thru device drivers that initialise d_mmap. I've got an example but it only has 1 page of status info so the allocation is a bit different. I'll see what I can find. --=20 Peter Jeremy Please excuse any delays as the result of my ISP's inability to implement an MTA that is either RFC2821-compliant or matches their claimed behaviour. --4jXrM3lyYWu4nBt5 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (FreeBSD) iEYEARECAAYFAklWvo4ACgkQ/opHv/APuIdN4QCfVFZrf/ucRKepOXUD3lAgXpFi Wa8AoMOKSKUUVd2vWBcfpY3duRoSrdSZ =F8xE -----END PGP SIGNATURE----- --4jXrM3lyYWu4nBt5--
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