[OE-core] [PATCH 02/16] kernel.bbclass: fix buildpath QA issue
Mark Hatle
mark.hatle at windriver.com
Tue Mar 22 16:57:41 UTC 2016
On 3/22/16 11:49 AM, Bruce Ashfield wrote:
>
>
> On Tue, Mar 22, 2016 at 12:18 PM, Mark Hatle <mark.hatle at windriver.com
> <mailto:mark.hatle at windriver.com>> wrote:
>
> On 3/22/16 7:21 AM, Bruce Ashfield wrote:
> >
> >
> > On Tue, Mar 22, 2016 at 8:12 AM, Hongxu Jia <hongxu.jia at windriver.com <mailto:hongxu.jia at windriver.com>
> > <mailto:hongxu.jia at windriver.com <mailto:hongxu.jia at windriver.com>>> wrote:
> >
> > Since CFLAGS CPPFLAGS CXXFLAGS has been unset, variable DEBUG_FLAGS could
> > not been passed to compiler, so we explicitly add DEBUG_FLAGS to CC to
> > replace build path with target path.
> >
> >
> > Can you be more explicit here ? What is typically contained in DEBUG_FLAGS ? The
> > kernel builds its own compiler line and flags, so anything you are setting from this
> > environment, should not be leaking into the kernel build.
> >
> > .. which leaves me wondering, what exactly is in DEBUG_FLAGS, and how is it
> > actually fixing the QA issue ?
>
> The specific debug flag in question is being added to remap the on-disk path to
> the path we want the items to look like from a debugging point of view.
>
> The typical format of DEBUG_FLAGS is something like:
>
> DEBUG_FLAGS ?= "-g -feliminate-unused-debug-types"
>
> This was recently updated to include the remapping:
>
> DEBUG_FLAGS ?= "-g -feliminate-unused-debug-types \
> -fdebug-prefix-map=${WORKDIR}=/usr/src/debug \
> -fdebug-prefix-map=${STAGING_DIR_NATIVE}= \
> -fdebug-prefix-map=${STAGING_DIR_HOST}= \
>
> The idea is the WORKDIR is replaced with '/usr/src/debug' inside of the binary
> and any debug symbol references. This makes it much easier for the system to
> work with supplied debug sources/symbols.
>
> I'm not sure you want to use DEBUG_FLAGS since anything can be put in there....
>
> Application space code should always use the DEBUG_FLAGS, or I think it's likely
> a bug.
>
> The kernel though should probably define it's own flag(s). Most likely you'll
> want something simple like:
>
> -fdebug-prefix-map=${WORKDIR}=/usr/src/debug
>
>
>
> I can see that.
>
> What outputs of the kernel build need this remapping ? The userspace parts ?
> Something else ?
The mapping affects __FILE__ references, internal dwarf symbols, etc.
So you need to have a mapping that covers the source and any intermediate
objects. In the general case using WORKDIR (as above) results in:
/usr/src/debug/<source>
/usr/src/debug/<build>
(This isn't right and I'll be commenting on the patch about that.. since it
should be wrapped in a package/version...)
Typically in YP 2.0 and before, the format was:
/usr/src/debug/<recipe>/<version>/[directories]
> The point is that we patch the kernel build, or make a specific Kconfig option, or
> something similar to that, versus leaking our build flags into the kernel build or
> "bad things can happen".
I agree.. this flag change needs to be unique to the kernel environment. The
key thing is that you want the kernel's internal file references __FILE__, dwarf
symbols, etc to have the format of an on-target filesystem location that can be
filled out.
> So I'm sure the solution in the build is the same, but passing flags via a general
> mechanism like I saw in the patch is generally not a good idea.
Agree.
--Mark
> Bruce
>
>
>
> Then all of the internal references to WORKDIR will be replaced with
> '/usr/src/debug' which cross gdb can 'map' or on-target will actually look in
> that location. (A corresponding '-dbg' package should be provided with the
> matching compilation sources at the local specified.)
>
> --Mark
>
> > Bruce
> >
> >
> >
> > [YOCTO #7058]
> >
> > Signed-off-by: Hongxu Jia <hongxu.jia at windriver.com <mailto:hongxu.jia at windriver.com>
> > <mailto:hongxu.jia at windriver.com <mailto:hongxu.jia at windriver.com>>>
> > ---
> > meta/classes/kernel.bbclass | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/meta/classes/kernel.bbclass b/meta/classes/kernel.bbclass
> > index c3eab50..d357ccf 100644
> > --- a/meta/classes/kernel.bbclass
> > +++ b/meta/classes/kernel.bbclass
> > @@ -207,7 +207,7 @@ kernel_do_compile() {
> > copy_initramfs
> >
> >
> use_alternate_initrd=CONFIG_INITRAMFS_SOURCE=${B}/usr/${INITRAMFS_IMAGE}-${MACHINE}.cpio
> > fi
> > - oe_runmake ${KERNEL_IMAGETYPE_FOR_MAKE} ${KERNEL_ALT_IMAGETYPE}
> > CC="${KERNEL_CC}" LD="${KERNEL_LD}" ${KERNEL_EXTRA_ARGS}
> $use_alternate_initrd
> > + oe_runmake ${KERNEL_IMAGETYPE_FOR_MAKE} ${KERNEL_ALT_IMAGETYPE}
> > CC="${KERNEL_CC} ${DEBUG_FLAGS}" LD="${KERNEL_LD}" ${KERNEL_EXTRA_ARGS}
> > $use_alternate_initrd
> > if test "${KERNEL_IMAGETYPE_FOR_MAKE}.gz" =
> "${KERNEL_IMAGETYPE}"; then
> > gzip -9c < "${KERNEL_IMAGETYPE_FOR_MAKE}" >
> "${KERNEL_OUTPUT}"
> > fi
> > @@ -216,7 +216,7 @@ kernel_do_compile() {
> > do_compile_kernelmodules() {
> > unset CFLAGS CPPFLAGS CXXFLAGS LDFLAGS MACHINE
> > if (grep -q -i -e '^CONFIG_MODULES=y$' ${B}/.config); then
> > - oe_runmake -C ${B} ${PARALLEL_MAKE} modules
> > CC="${KERNEL_CC}" LD="${KERNEL_LD}" ${KERNEL_EXTRA_ARGS}
> > + oe_runmake -C ${B} ${PARALLEL_MAKE} modules
> CC="${KERNEL_CC}
> > ${DEBUG_FLAGS}" LD="${KERNEL_LD}" ${KERNEL_EXTRA_ARGS}
> >
> > # Module.symvers gets updated during the
> > # building of the kernel modules. We need to
> > --
> > 1.9.1
> >
> > --
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> >
> >
> >
> >
> > --
> > "Thou shalt not follow the NULL pointer, for chaos and madness await thee
> at its
> > end"
>
>
>
>
> --
> "Thou shalt not follow the NULL pointer, for chaos and madness await thee at its
> end"
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