Date: Sat, 27 Sep 2014 13:19:22 -0700 From: Russell Haley <russ.haley@gmail.com> To: Tim Kientzle <tim@kientzle.com> Cc: freebsd-arm@freebsd.org Subject: Re: Digi CCWMX53 Message-ID: <CABx9NuTRwBHLYJb1NP3=X6TuLcbZ_KsUBsdNVq3GX2ffRs1_hA@mail.gmail.com> In-Reply-To: <A4CEAFC3-446E-4D14-8F3B-1CDC92C65829@kientzle.com> References: <CABx9NuQr%2BdEb_yj3ypEe6Sb_qPY%2BqP74n0x1K5=_K6Zoio2vkw@mail.gmail.com> <A4CEAFC3-446E-4D14-8F3B-1CDC92C65829@kientzle.com>
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Tim, Thanks, that's clarified a large number of my hanging questions. I thought I had read that clang didn't support cross compiling arm for freebsd in 10. Is this true? I should have some more shortly! Russ On Sat, Sep 27, 2014 at 11:53 AM, Tim Kientzle <tim@kientzle.com> wrote: > > 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. > > > > > 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.) > > > > > 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=xyz ... 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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