Thanks for the report. I'll try to see if I can find a ppc64le setup to replicate.

The Missing build-id messages seem bogus since they are for .o object files and those aren't supposed to have build-ids (only loadable ELF images should, like executables, shared libaries or kernel modules).

Are the vmlinuz and vmlinuz-4.11.0-0.rc1.git0.2.fc27.ppc64le files hard linked? Then the Duplicate build-id message is also bogus.

The Bad CSA data message indicate that no files were included in the cpioList (file list) of the package. Which might or might not be related to the build-id warnings.

I think this rpm patch might solve the issue:

diff --git a/build/files.c b/build/files.c
index cbcc0a9..26f53bd 100644
--- a/build/files.c
+++ b/build/files.c
@@ -1709,8 +1709,10 @@ static int generateBuildIDs(FileList fl)
 	if (lstat(flp->diskPath, &sbuf) == 0 && S_ISREG (sbuf.st_mode)) {
 	    int fd = open (flp->diskPath, O_RDONLY);
 	    if (fd >= 0) {
+		GElf_Ehdr ehdr;
 		Elf *elf = elf_begin (fd, ELF_C_READ, NULL);
-		if (elf != NULL && elf_kind(elf) == ELF_K_ELF) {
+		if (elf != NULL && elf_kind(elf) == ELF_K_ELF
+		    && gelf_getehdr(elf, &ehdr) != NULL) {
 		    const void *build_id;
 		    ssize_t len = dwelf_elf_gnu_build_id (elf, &build_id);
 		    /* len == -1 means error. Zero means no
@@ -1759,9 +1761,14 @@ static int generateBuildIDs(FileList fl)
 				   _("error reading build-id in %s: %s\n"),
 				   flp->diskPath, elf_errmsg (-1));
 			} else if (len == 0) {
-			    rpmlog(terminate ? RPMLOG_ERR : RPMLOG_WARNING,
-				   _("Missing build-id in %s\n"),
-				   flp->diskPath);
+			    /* Only ET_EXEC, ET_DYN or kernel modules
+			       have build-ids. */
+			    if (ehdr.e_type == ET_EXEC || ehdr.e_type == ET_DYN
+				|| (ehdr.e_type == ET_REL
+				    && rpmFileHasSuffix (flp->diskPath, ".ko")))
+			      rpmlog(terminate ? RPMLOG_ERR : RPMLOG_WARNING,
+				     _("Missing build-id in %s\n"),
+				     flp->diskPath);
 			} else {
 			    rpmlog(terminate ? RPMLOG_ERR : RPMLOG_WARNING,
 				   (len < 16

I'll see if I can find a way to test this on a ppc64le setup.

Better, but not enough:
    Duplicate build-ids /builddir/build/BUILDROOT/kernel-4.11.0-0.rc1.git1.1.fc27.ppc64le/lib/modules/4.11.0-0.rc1.git1.1.fc27.ppc64le/vmlinuz and /builddir/build/BUILDROOT/kernel-4.11.0-0.rc1.git1.1.fc27.ppc64le/boot/vmlinuz-4.11.0-0.rc1.git1.1.fc27.ppc64le
    Duplicate build-ids /builddir/build/BUILDROOT/kernel-4.11.0-0.rc1.git1.1.fc27.ppc64le/usr/lib/debug/usr/lib/debug/lib/modules/4.11.0-0.rc1.git1.1.fc27.ppc64le/vmlinux.debug and /builddir/build/BUILDROOT/kernel-4.11.0-0.rc1.git1.1.fc27.ppc64le/usr/lib/debug/lib/modules/4.11.0-0.rc1.git1.1.fc27.ppc64le/vmlinux
    create archive failed: cpio: (error 0xffffffff)

So that patch definitely helped to get rid of those missing build-id errors.
And it has already been integrated upstream.

But there is still something odd going on. See https://copr-be.cloud.fedoraproject.org/results/ignatenkobrain/debuginfo-kernel-ppc64le/fedora-rawhide-ppc64le/00523940-kernel/build.log.gz

Processing files: kernel-debuginfo-4.11.0-0.rc1.git1.1.fc27.ppc64le
warning: Duplicate build-ids /builddir/build/BUILDROOT/kernel-4.11.0-0.rc1.git1.1.fc27.ppc64le/usr/lib/debug/usr/lib/debug/lib/modules/4.11.0-0.rc1.git1.1.fc27.ppc64le/vmlinux.debug and /builddir/build/BUILDROOT/kernel-4.11.0-0.rc1.git1.1.fc27.ppc64le/usr/lib/debug/lib/modules/4.11.0-0.rc1.git1.1.fc27.ppc64le/vmlinux
Provides: installonlypkg(kernel) kernel-debuginfo = 4.11.0-0.rc1.git1.1.fc27 kernel-debuginfo(ppc-64) = 4.11.0-0.rc1.git1.1.fc27 kernel-debuginfo-ppc64le = 4.11.0-0.rc1.git1.1.fc27
Requires(rpmlib): rpmlib(CompressedFileNames) <= 3.0.4-1 rpmlib(FileDigests) <= 4.6.0-1 rpmlib(PayloadFilesHavePrefix) <= 4.0-1
Checking for unpackaged file(s): /usr/lib/rpm/check-files /builddir/build/BUILDROOT/kernel-4.11.0-0.rc1.git1.1.fc27.ppc64le
Wrote: /builddir/build/RPMS/kernel-4.11.0-0.rc1.git1.1.fc27.ppc64le.rpm
Wrote: /builddir/build/RPMS/kernel-headers-4.11.0-0.rc1.git1.1.fc27.ppc64le.rpm
Wrote: /builddir/build/RPMS/kernel-cross-headers-4.11.0-0.rc1.git1.1.fc27.ppc64le.rpm
error: create archive failed: cpio: (error 0xffffffff)
RPM build errors:
    line 903: Possible unexpanded macro in: %package %{pae}-core
    line 903: Possible unexpanded macro in: Provides: kernel-%{pae}-core-uname-r = 4.11.0-0.rc1.git1.1.fc27.ppc64le+%{pae}
    line 903: Possible unexpanded macro in: Provides: kernel-ppc64le = 4.11.0-0.rc1.git1.1.fc27+%{pae}
    line 903: Possible unexpanded macro in: Provides: kernel-uname-r = 4.11.0-0.rc1.git1.1.fc27.ppc64le+%{pae}
    line 903: Possible unexpanded macro in: %package %{pae}
    line 903: Possible unexpanded macro in: Requires: kernel-%{pae}-core-uname-r = 4.11.0-0.rc1.git1.1.fc27.ppc64le+%{pae}
    line 903: Possible unexpanded macro in: Requires: kernel-%{pae}-modules-uname-r = 4.11.0-0.rc1.git1.1.fc27.ppc64le+%{pae}
    line 903: Possible unexpanded macro in: %package %{pae}-devel
    line 903: Possible unexpanded macro in: Provides: kernel-devel-ppc64le = 4.11.0-0.rc1.git1.1.fc27+%{pae}
    line 903: Possible unexpanded macro in: Provides: kernel-devel-uname-r = 4.11.0-0.rc1.git1.1.fc27.ppc64le+%{pae}
    line 903: Possible unexpanded macro in: %package %{pae}-modules
    line 903: Possible unexpanded macro in: Provides: kernel-modules-ppc64le = 4.11.0-0.rc1.git1.1.fc27+%{pae}
    line 903: Possible unexpanded macro in: Provides: kernel-modules = 4.11.0-0.rc1.git1.1.fc27+%{pae}
    line 903: Possible unexpanded macro in: Provides: kernel-%{pae}-modules-uname-r = 4.11.0-0.rc1.git1.1.fc27.ppc64le+%{pae}
    line 903: Possible unexpanded macro in: Requires: kernel-uname-r = 4.11.0-0.rc1.git1.1.fc27.ppc64le+%{pae}
    line 903: Possible unexpanded macro in: %package %{pae}-modules-extra
    line 903: Possible unexpanded macro in: Provides: kernel-%{pae}-modules-extra-ppc64le = 4.11.0-0.rc1.git1.1.fc27+%{pae}
    line 903: Possible unexpanded macro in: Provides: kernel-%{pae}-modules-extra = 4.11.0-0.rc1.git1.1.fc27+%{pae}
    line 903: Possible unexpanded macro in: Provides: kernel-%{pae}-modules-extra-uname-r = 4.11.0-0.rc1.git1.1.fc27.ppc64le+%{pae}
    line 903: Possible unexpanded macro in: Requires: kernel-uname-r = 4.11.0-0.rc1.git1.1.fc27.ppc64le+%{pae}
    line 903: Possible unexpanded macro in: Requires: kernel-%{pae}-modules-uname-r = 4.11.0-0.rc1.git1.1.fc27.ppc64le+%{pae}
    line 903: Possible unexpanded macro in: %package %{pae}-debuginfo
    line 919: Possible unexpanded macro in: %package %{pae}debug-core
    line 919: Possible unexpanded macro in: Provides: kernel-%{pae}debug-core-uname-r = 4.11.0-0.rc1.git1.1.fc27.ppc64le+%{pae}debug
    line 919: Possible unexpanded macro in: Provides: kernel-ppc64le = 4.11.0-0.rc1.git1.1.fc27+%{pae}debug
    line 919: Possible unexpanded macro in: Provides: kernel-uname-r = 4.11.0-0.rc1.git1.1.fc27.ppc64le+%{pae}debug
    line 919: Possible unexpanded macro in: %package %{pae}debug
    line 919: Possible unexpanded macro in: Requires: kernel-%{pae}debug-core-uname-r = 4.11.0-0.rc1.git1.1.fc27.ppc64le+%{pae}debug
    line 919: Possible unexpanded macro in: Requires: kernel-%{pae}debug-modules-uname-r = 4.11.0-0.rc1.git1.1.fc27.ppc64le+%{pae}debug
    line 919: Possible unexpanded macro in: %package %{pae}debug-devel
    line 919: Possible unexpanded macro in: Provides: kernel-devel-ppc64le = 4.11.0-0.rc1.git1.1.fc27+%{pae}debug
    line 919: Possible unexpanded macro in: Provides: kernel-devel-uname-r = 4.11.0-0.rc1.git1.1.fc27.ppc64le+%{pae}debug
    line 919: Possible unexpanded macro in: %package %{pae}debug-modules
    line 919: Possible unexpanded macro in: Provides: kernel-modules-ppc64le = 4.11.0-0.rc1.git1.1.fc27+%{pae}debug
    line 919: Possible unexpanded macro in: Provides: kernel-modules = 4.11.0-0.rc1.git1.1.fc27+%{pae}debug
    line 919: Possible unexpanded macro in: Provides: kernel-%{pae}debug-modules-uname-r = 4.11.0-0.rc1.git1.1.fc27.ppc64le+%{pae}debug
    line 919: Possible unexpanded macro in: Requires: kernel-uname-r = 4.11.0-0.rc1.git1.1.fc27.ppc64le+%{pae}debug
    line 919: Possible unexpanded macro in: %package %{pae}debug-modules-extra
    line 919: Possible unexpanded macro in: Provides: kernel-%{pae}debug-modules-extra-ppc64le = 4.11.0-0.rc1.git1.1.fc27+%{pae}debug
    line 919: Possible unexpanded macro in: Provides: kernel-%{pae}debug-modules-extra = 4.11.0-0.rc1.git1.1.fc27+%{pae}debug
    line 919: Possible unexpanded macro in: Provides: kernel-%{pae}debug-modules-extra-uname-r = 4.11.0-0.rc1.git1.1.fc27.ppc64le+%{pae}debug
    line 919: Possible unexpanded macro in: Requires: kernel-uname-r = 4.11.0-0.rc1.git1.1.fc27.ppc64le+%{pae}debug
    line 919: Possible unexpanded macro in: Requires: kernel-%{pae}debug-modules-uname-r = 4.11.0-0.rc1.git1.1.fc27.ppc64le+%{pae}debug
    line 919: Possible unexpanded macro in: %package %{pae}debug-debuginfo
    Duplicate build-ids /builddir/build/BUILDROOT/kernel-4.11.0-0.rc1.git1.1.fc27.ppc64le/lib/modules/4.11.0-0.rc1.git1.1.fc27.ppc64le/vmlinuz and /builddir/build/BUILDROOT/kernel-4.11.0-0.rc1.git1.1.fc27.ppc64le/boot/vmlinuz-4.11.0-0.rc1.git1.1.fc27.ppc64le
    Duplicate build-ids /builddir/build/BUILDROOT/kernel-4.11.0-0.rc1.git1.1.fc27.ppc64le/usr/lib/debug/usr/lib/debug/lib/modules/4.11.0-0.rc1.git1.1.fc27.ppc64le/vmlinux.debug and /builddir/build/BUILDROOT/kernel-4.11.0-0.rc1.git1.1.fc27.ppc64le/usr/lib/debug/lib/modules/4.11.0-0.rc1.git1.1.fc27.ppc64le/vmlinux
    create archive failed: cpio: (error 0xffffffff)
Child return code was: 1

(In reply to Igor Gnatenko from comment #3)
> Better, but not enough:
>     Duplicate build-ids
> /builddir/build/BUILDROOT/kernel-4.11.0-0.rc1.git1.1.fc27.ppc64le/lib/
> modules/4.11.0-0.rc1.git1.1.fc27.ppc64le/vmlinuz and
> /builddir/build/BUILDROOT/kernel-4.11.0-0.rc1.git1.1.fc27.ppc64le/boot/
> vmlinuz-4.11.0-0.rc1.git1.1.fc27.ppc64le
>     Duplicate build-ids
> /builddir/build/BUILDROOT/kernel-4.11.0-0.rc1.git1.1.fc27.ppc64le/usr/lib/
> debug/usr/lib/debug/lib/modules/4.11.0-0.rc1.git1.1.fc27.ppc64le/vmlinux.
> debug and
> /builddir/build/BUILDROOT/kernel-4.11.0-0.rc1.git1.1.fc27.ppc64le/usr/lib/
> debug/lib/modules/4.11.0-0.rc1.git1.1.fc27.ppc64le/vmlinux
>     create archive failed: cpio: (error 0xffffffff)

I think those Duplicate build-ids are harmless since they should only be warnings. Although it would definitely be better if we understood why that happens.

The real error seems to the the cpio archive creation failure.

It is a pity we don't have access to a ppc64le kernel buildroot to better investigate what is going on.

*** Bug 1430764 has been marked as a duplicate of this bug. ***

The patch in comment #2 was subtly wrong, but had the correct idea.
It was wrong because it suppressed the bad warning/error message, but then still failed... Making it harder to understand what was going on.

Followup patch that corrects the actual error posted, but hasn't shown up in the archives yet: 
http://lists.rpm.org/pipermail/rpm-maint/2017-March/date.html

With that both the ppc64 kernel package and the LibRaw both build without issue. In both cases it was triggered by a .o object file that was added to the binary package (and which was erroneously flagged for not having a build-id).

(In reply to Mark Wielaard from comment #7)
> The patch in comment #2 was subtly wrong, but had the correct idea.
> It was wrong because it suppressed the bad warning/error message, but then
> still failed... Making it harder to understand what was going on.
> 
> Followup patch that corrects the actual error posted, but hasn't shown up in
> the archives yet: 
> http://lists.rpm.org/pipermail/rpm-maint/2017-March/date.html

Sorry, it was. I had the archive upside down:

http://lists.rpm.org/pipermail/rpm-maint/2017-March/005233.html
And it has now also been applied upstream:
http://lists.rpm.org/pipermail/rpm-maint/2017-March/005235.html