Implement --enable-debuginfo to force debuginfo
Inspection of a Ubuntu 14.04 x64 system revealed that the config file used to build the kernel image differs from the config file used to build kernel modules by the presence of CONFIG_DEBUG_INFO=y: This in itself is insufficient to show that the kernel is built with debuginfo, but a cursory analysis of the debuginfo provided and the size of the kernel strongly suggests that it was built with CONFIG_DEBUG_INFO=y while the modules were not. Installing linux-image-$(uname -r)-dbgsym had no obvious effect on the debuginfo provided by either the modules or the kernel. The consequence is that issue reports from distributions such as Ubuntu and its derivatives build kernel modules without debuginfo contain nonsensical backtraces. It is therefore desireable to force generation of debuginfo, so we implement --enable-debuginfo. Since the build system can build both userspace components and kernel modules, the generic --enable-debuginfo option will force debuginfo for both. However, it also supports --enable-debuginfo=kernel and --enable-debuginfo=user for finer grained control. Enabling debuginfo for the kernel modules works by injecting CONFIG_DEBUG_INFO=y into the make environment. This is enables generation of debuginfo by the kernel build systems on all Linux kernels, but the build environment is slightly different int hat CONFIG_DEBUG_INFO has not been in the CPP. Adding -DCONFIG_DEBUG_INFO would fix that, but it would also cause build failures on kernels where CONFIG_DEBUG_INFO=y is already set. That would complicate its use in DKMS environments that support a range of kernels and is therefore undesireable. We could write a compatibility shim to enable CONFIG_DEBUG_INFO only when it is explicitly disabled, but we forgo doing that because it is unnecessary. Nothing in ZoL or the kernel uses CONFIG_DEBUG_INFO in the CPP at this time and that is unlikely to change. Enabling debuginfo for the userspace components is done by injecting -g into CPPFLAGS. This is not necessary because the build system honors the environment's CPPFLAGS by appending them to the actual CPPFLAGS used, but it is supported for consistency. Reviewed-by: Chunwei Chen <tuxoko@gmail.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Richard Yao <richard.yao@clusterhq.com> Closes #2734
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@ -38,12 +38,43 @@ AC_DEFUN([ZFS_AC_DEBUG], [
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[ZFS_AC_DEBUG_DISABLE],
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[AC_MSG_ERROR([Unknown option $enable_debug])])
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AC_SUBST(DEBUG_CFLAGS)
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AC_SUBST(DEBUG_STACKFLAGS)
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AC_SUBST(DEBUG_ZFS)
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AC_MSG_RESULT([$enable_debug])
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])
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AC_DEFUN([ZFS_AC_DEBUGINFO_KERNEL], [
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KERNELMAKE_PARAMS="$KERNELMAKE_PARAMS CONFIG_DEBUG_INFO=y"
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])
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AC_DEFUN([ZFS_AC_DEBUGINFO_USER], [
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DEBUG_CFLAGS="$DEBUG_CFLAGS -g"
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])
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AC_DEFUN([ZFS_AC_DEBUGINFO], [
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AC_MSG_CHECKING([whether debuginfo support will be forced])
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AC_ARG_ENABLE([debuginfo],
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[AS_HELP_STRING([--enable-debuginfo],
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[Force generation of debuginfo @<:@default=no@:>@])],
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[],
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[enable_debuginfo=no])
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AS_CASE(["x$enable_debuginfo"],
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["xyes"],
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[ZFS_AC_DEBUGINFO_KERNEL
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ZFS_AC_DEBUGINFO_USER],
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["xkernel"],
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[ZFS_AC_DEBUGINFO_KERNEL],
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["xuser"],
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[ZFS_AC_DEBUGINFO_USER],
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["xno"],
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[],
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[AC_MSG_ERROR([Unknown option $enable_debug])])
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AC_SUBST(DEBUG_CFLAGS)
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AC_MSG_RESULT([$enable_debuginfo])
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])
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AC_DEFUN([ZFS_AC_CONFIG_ALWAYS], [
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ZFS_AC_CONFIG_ALWAYS_NO_UNUSED_BUT_SET_VARIABLE
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ZFS_AC_CONFIG_ALWAYS_NO_BOOL_COMPARE
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@ -55,6 +55,7 @@ ZFS_AC_LICENSE
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ZFS_AC_PACKAGE
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ZFS_AC_CONFIG
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ZFS_AC_DEBUG
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ZFS_AC_DEBUGINFO
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AC_CONFIG_FILES([
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Makefile
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