Date: Sat, 27 Sep 2014 11:53:35 -0700 From: Tim Kientzle <tim@kientzle.com> To: Russell Haley <russ.haley@gmail.com> Cc: freebsd-arm@freebsd.org Subject: Re: Digi CCWMX53 Message-ID: <A4CEAFC3-446E-4D14-8F3B-1CDC92C65829@kientzle.com> In-Reply-To: <CABx9NuQr%2BdEb_yj3ypEe6Sb_qPY%2BqP74n0x1K5=_K6Zoio2vkw@mail.gmail.com> References: <CABx9NuQr%2BdEb_yj3ypEe6Sb_qPY%2BqP74n0x1K5=_K6Zoio2vkw@mail.gmail.com>
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On Sep 26, 2014, at 10:38 PM, Russell Haley <russ.haley@gmail.com> = wrote: > 1) Can anyone give me the correct u-boot enviroment variables or = reference > to the u-boot process to boot the completed freebsd kernel. = Specifically on > a CCWMX53 if possible, but I have linux references to port from. Where > would I look for an example? There are two general approaches being used: 1) Have U-Boot load and boot the kernel directly. This can sometimes be = done with an unmodified Linux U-Boot. 2) Have U-Boot load FreeBSDs scriptable 'ubldr' and have that load the = kernel. This provides more flexibility in the boot process but usually = requires rebuilding U-Boot. In particular, you'll need to: * Add CONFIG_CMD_ELF option to U-Boot so it can load `ubldr' which is = an ELF executable * Add CONFIG_CMD_API option to U-Boot so `ubldr' can access U-Boot's = drivers for hardware access (`ubldr' itself has to be compiled for each = board to adjust the load address but is otherwise completely generic). * Adjust the U-Boot startup scripts to set FDT environment variables = and load ubldr. You can look at the U-Boot patches for various boards = supported by Crochet to see how this has been done elsewhere: github.com/kientlze/crochet-freebsd > 2) Do I need to create a cross compiler? Reference 1 says yes, = reference > two says no. Help! In most cases, the FreeBSD build system will build a cross-compiler for = it's own use, so you generally don't need to install a cross compiler to = cross-build FreeBSD proper. However, U-Boot is not part of FreeBSD so = you may need to install a separate cross-compiler to build that. >=20 > Ref.1 Build a cross compiler > https://wiki.freebsd.org/FreeBSD/arm/ArndaleBoard This is using a cross-compiler from ports to build U-Boot. It uses the = FreeBSD build machinery to cross-build the FreeBSD kernel and world. = (When you specify TARGET_ARCH, FreeBSD's 'buildworld' target will build = and use a suitable cross-compiler. Also, 'buildkernel' will reuse the = cross-compiler built by 'buildworld', so you do not need = 'kernel-toolchain' as long as you 'buildworld' first.) >=20 > Ref 2. No cross compiler/ make toolchain > https://wiki.freebsd.org/A_Brief_Guide_To_Cross_Compiling_FreeBSD This example only talks about building *world*, and the 'buildworld' = target builds the necessary cross-tools transparently. In particular, = since it doesn't talk about building out-of-tree boot loaders such as = U-Boot, it does not need to talk about building/installing an explicit = cross-compiler. For cross-compilers, you have three options: * Ports. * After a successful buildworld, you can 'make TARGET=3Dxyz ... = buildenv' to get a shell with suitable path settings to reuse the = cross-tools from the buildworld stage. Use 'buildenvvar' to just get = the environment for use in scripts. * FreeBSD source has an 'xdev' target that builds and installs a set of = cross-tools. In particular, it can install cross-versions of the same = GCC or clang used by the rest of FreeBSD. This facility has changed a = lot recently, so ask if you need the current command line. Hope this clarifies things, Tim
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