Date: Sun, 20 May 2012 10:47:04 -0700 From: Tim Kientzle <kientzle@freebsd.org> To: freebsd-current FreeBSD <freebsd-current@freebsd.org>, arm@freebsd.org Subject: Customizing ubldr build... Message-ID: <E84EA543-11A9-4EA6-9313-6908F485C569@freebsd.org>
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In order to fully automate building SD images for Beaglebone,
I'm trying to come up with a clean way to tailor the ubldr build.
I think I've come up with a good way to do this and would appreciate any =
feedback.
First, here's the (somewhat simplified) script that builds and installs =
ubldr (this
is going into the beaglebsd.sh script I've been working on):
cd /usr/src
buildenv=3D`make TARGET_ARCH=3Darm TARGET_CPUTYPE=3Darm buildenvvars`
cd sys/boot
eval $buildenv make obj
eval $buildenv make UBLDR_LOADADDR=3D0x80100000 all
cd arm/uboot
eval $buildenv make DESTDIR=3D${DESTDIR} BINDIR=3D NO_MAN=3Dtrue =
install
The key issue is the physical load address, which differs among boards.
My idea is to allow specifying this at build time through a make
variable UBLDR_LOADADDR.
The Makefile for sys/boot/arm/uboot passes this down into a
dynamically-built loader script. Here's a summary of the changes
I'm proposing to sys/boot/arm/uboot/Makefile:
+UBLDR_LOADADDR?=3D 0x1000000
=20
LDFLAGS=3D -nostdlib -static
+LDFLAGS+=3D -T ldscript.generated
LDFLAGS+=3D -T ${.CURDIR}/ldscript.${MACHINE_CPUARCH}
=20
+${PROG}: ldscript.generated
+
+ldscript.generated::
+ echo "UBLDR_LOADADDR =3D ${UBLDR_LOADADDR};" > =
ldscript.generated
And now the standard loader script can simply use the symbol instead of
a hard-coded value:
Index: ldscript.arm
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
--- ldscript.arm (revision 235597)
+++ ldscript.arm (working copy)
@@ -5,7 +5,7 @@
SECTIONS
{
/* Read-only sections, merged into text segment: */
- . =3D 0x1000000 + SIZEOF_HEADERS;
+ . =3D UBLDR_LOADADDR + SIZEOF_HEADERS;
.interp : { *(.interp) }
.hash : { *(.hash) }
.dynsym : { *(.dynsym) }
This seems to work pretty well for me, except for one odd point:
the make dependencies cause ubldr to get relinked on every build.
(This can be fixed in the usual way.)
If anyone sees a better way to handle this, I'd much appreciate the =
input.
Cheers,
Tim
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