Date: Sun, 3 Mar 2013 11:43:21 -0800 From: Tim Kientzle <kientzle@freebsd.org> To: freebsd-arm@freebsd.org Subject: GENERIC kernel issues Message-ID: <DF7B73D4-BE50-4E75-8D5B-FE19A4764F31@freebsd.org>
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--Apple-Mail=_F90B5CAF-B0AA-4609-AF80-4A91CA3659E3 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=us-ascii I spent some time yesterday putting together a kernel configuration for a GENERIC ARM kernel that would support both RaspberryPi and BeagleBone. Just to see how far I could get. Here's a list of the problems I've found so far: ** Multiple MMU support. If you put these two lines into an ARM kernel config, the build will fail in the MMU code: cpu CPU_ARM1176 cpu CPU_CORTEXA Basically, this turns on the support for multiple MMUs but the ARMv6/ARMv7 MMU definitions don't play nicely with run-time MMU selection. ** PHYSADDR/KERNPHYSADDR hardwiring. Ian has made a lot of progress and I'm working on some related changes to address this. I think we understand how to eliminate these constants and replace them with run-time detection of the load address. I'm still not sure what changes might be needed to the loader to make this work. ** PIPT vs. VIVT cache management. This is currently set at compile time; we'll need to have a way to set this at run time based on the CPU. (I have some skeletal code to select CPU at the top of initarm by inspecting the FDT. I presume this switch will be routine once a robust version of that is in place.) ** TI processor detection. This is currently hardwired at build time, so we cannot currently build a kernel that supports both AM335x and OMAP4, for example. Question: should we create a /projects/arm-generic/ branch to hold this work while it's in flux? Tim --Apple-Mail=_F90B5CAF-B0AA-4609-AF80-4A91CA3659E3 Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP using GPGMail -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.18 (Darwin) iQEcBAEBAgAGBQJRM6faAAoJEGMNyGo0rfFBdfAH/R7xOKp9xQ2zz8FSKT7M6lan VOf6ArQqMpfNkaUyr4lmAN5NNAkXWLmc4H78RrL6aWQHTEqH+xAFaQTnthZzCTOF bRC3olzQGCbhP7IBn51Z9waYa8Q/PRKdBbApEPaL2mOzX0XHvipIXn3GAZgxVCv7 YZnuiPfCAkWOiZMWBpLdKK2Jo9DZBPKSfKzxHqYLUbG0H2FyJmgUsHi35MQJiDKq VWe8KQ9jEneu+HO5V3xEsS1Yd1m873w7e0TjhIteWH1MqnDQd1MGcF1oO+u+naAa WjvBcEcuuTQaAi07Ii8H4iJn3pATg+Q6q5RX8MOSsj7Ih3mjBwRnE37GV26X8Us= =zsr9 -----END PGP SIGNATURE----- --Apple-Mail=_F90B5CAF-B0AA-4609-AF80-4A91CA3659E3--
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