[v2] rpm: Allow setting platform macro settings externally

diff --git a/meta/recipes-devtools/rpm/files/0001-Allow-setting-platform-macro-settings-externally.patch b/meta/recipes-devtools/rpm/files/0001-Allow-setting-platform-macro-settings-externally.patch
new file mode 100644
index 0000000000..0e5f9e3af1
--- /dev/null
+++ b/meta/recipes-devtools/rpm/files/0001-Allow-setting-platform-macro-settings-externally.patch
@@ -0,0 +1,107 @@ 
+From 98a7615d9db2d43126c453b9bd0f4cc5006c18b7 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Zolt=C3=A1n=20B=C3=B6sz=C3=B6rm=C3=A9nyi?=
+ <zboszor@gmail.com>
+Date: Tue, 25 Jul 2023 10:56:44 +0200
+Subject: [PATCH] Allow setting platform macro settings externally
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+By default, rpm installs a series of default platforms based on
+the CPU architecture names in subdirectories called
+
+    /usr/lib/platform/<arch>-linux
+
+This is enough for regular Linux distributions. However, some
+distributions may use more specific platform names that refer to
+particular computer systems, like SBCs or specific CPU tuning when
+compiling.
+
+If the platform subdirectory does not exist in /usr/lib/platform
+then rpmbuild does not work.
+
+Allow creating such custom platform subdirectory with feeding
+the necessary data using external variables: RPM_CUSTOM_ARCH,
+RPM_CUSTOM_ISANAME, RPM_CUSTOM_ISABITS, RPM_CUSTOM_CANONARCH
+and RPM_CUSTOM_CANONCOLOR
+
+Signed-off-by: Zoltán Böszörményi <zboszor@gmail.com>
+Upstream-Status: Submitted [https://github.com/rpm-software-management/rpm/pull/2585]
+---
+ INSTALL         | 32 ++++++++++++++++++++++++++++++++
+ installplatform |  9 ++++++++-
+ 2 files changed, 40 insertions(+), 1 deletion(-)
+
+diff --git a/INSTALL b/INSTALL
+index 0edbc32e7..163b93ff0 100644
+--- a/INSTALL
++++ b/INSTALL
+@@ -143,6 +143,38 @@ and then install with:
+ 
+     make install
+ 
++By default, rpm installs a series of default platforms based on the CPU
++architecture names in subdirectories called
++
++    /usr/lib/platform/<arch>-linux
++
++This is enough for regular Linux distributions. However, some distributions
++may use more specific platform names that refer to particular computer
++systems, like SBCs or specific CPU tuning when compiling. Examples of such
++platform names are: "genericx86_64", "intel_skylake_64", "raspberrypi_armv7",
++"raspberrypi_armv8", etc.
++
++If the platform name is put into /etc/rpm/platform, then rpmbuild uses it
++and the only macros file rpmbuild looks for is
++
++    /usr/lib/platform/`cat /etc/rpm/platform`-linux/macros
++
++If this file does not exist, many rpm macros will not have their expected
++values set and e.g. %configure will fail when trying to run rpmbuild.
++
++To allow creating the macros file for such a custom platform, the shell
++variables listed below must be set. If RPM_CUSTOM_ARCH is not set, the rest
++is ignored.
++
++    export RPM_CUSTOM_ARCH=genericx86_64
++    export RPM_CUSTOM_ISANAME=x86
++    export RPM_CUSTOM_ISABITS=64
++    export RPM_CUSTOM_CANONARCH=x86_64
++    export RPM_CUSTOM_CANONCOLOR=0 # to use /usr/lib for %_libdir
++    export RPM_CUSTOM_CANONCOLOR=3 # to use /usr/lib64 for %_libdir
++
++    make install # this also installs /usr/lib/platform/genericx86_64-linux/macros
++
+ Rpm comes with an automated self-test suite. The test-suite requires
+ autom4te from autoconf (https://www.gnu.org/software/autoconf/) and
+ bwrap (https://github.com/containers/bubblewrap/). It is enabled by
+diff --git a/installplatform b/installplatform
+index c44055d9f..ac9b61643 100755
+--- a/installplatform
++++ b/installplatform
+@@ -11,7 +11,7 @@ VENDOR="${4}"
+ OS="${5}"
+ RPMRC_GNU="${6}"
+ 
+-for ARCH in noarch `grep ^arch_canon $RPMRC | cut -d: -f2`; do
++for ARCH in noarch `grep ^arch_canon $RPMRC | cut -d: -f2` ${RPM_CUSTOM_ARCH:+custom}; do
+   RPMRC_OPTFLAGS="`sed -n 's/^optflags: '$ARCH' //p' $RPMRC`"
+   RPMRC_OPTFLAGS="`echo $RPMRC_OPTFLAGS | sed -e 's, ,\ ,g'`"
+   case $RPMRC_OPTFLAGS in
+@@ -30,6 +30,13 @@ for ARCH in noarch `grep ^arch_canon $RPMRC | cut -d: -f2`; do
+   CANONCOLOR=
+   FILTER=cat
+   case "${ARCH}" in
++    custom)
++	ARCH=$RPM_CUSTOM_ARCH
++	ISANAME=$RPM_CUSTOM_ISANAME
++	ISABITS=$RPM_CUSTOM_ISABITS
++	CANONARCH=$RPM_CUSTOM_CANONARCH
++	CANONCOLOR=$RPM_CUSTOM_CANONCOLOR
++    ;;
+     sparc64*) 
+ 	ISANAME=sparc
+ 	ISABITS=64
+-- 
+2.41.0
+
diff --git a/meta/recipes-devtools/rpm/rpm_4.18.1.bb b/meta/recipes-devtools/rpm/rpm_4.18.1.bb
index 95a9e92f96..97dd843e56 100644
--- a/meta/recipes-devtools/rpm/rpm_4.18.1.bb
+++ b/meta/recipes-devtools/rpm/rpm_4.18.1.bb
@@ -40,6 +40,7 @@  SRC_URI = "git://github.com/rpm-software-management/rpm;branch=rpm-4.18.x;protoc
            file://0001-python-Use-Py_hash_t-instead-of-long-in-hdr_hash.patch \
            file://fix-declaration.patch \
            file://ea3187cfcf9cac87e5bc5e7db79b0338da9e355e.patch \
+           file://0001-Allow-setting-platform-macro-settings-externally.patch \
            "
 
 PE = "1"
@@ -128,10 +129,29 @@  do_install:append:class-nativesdk() {
 	EOF
 }
 
+def rpm_isaname(d):
+    import re
+    arch = d.getVar('TARGET_ARCH')
+    if re.match("^i.86$", arch) or re.match("^x86.*64$", arch):
+        return "x86"
+    # Add more platform tweaks for ISANAME as needed
+    return arch
+
+# Add the custom BSP platform "macros" file
+do_install:prepend:class-target() {
+    export RPM_CUSTOM_ARCH = "${MACHINE_ARCH}"
+    export RPM_CUSTOM_ISANAME = "${@rpm_isaname(d)}"
+    export RPM_CUSTOM_ISABITS = "${SITEINFO_BITS}"
+    export RPM_CUSTOM_CANONARCH = "${TARGET_ARCH}"
+    # CANONCOLOR determines whether /usr/lib or /usr/lib64 is used for a 64-bit platform
+    export RPM_CUSTOM_CANONCOLOR = "${@bb.utils.contains('DISTRO_FEATURES', 'multilib', '3', '0', d)}"
+}
+
 # Rpm's make install creates var/tmp which clashes with base-files packaging
 do_install:append:class-target() {
     rm -rf ${D}/var
 }
+
 do_install:append:class-nativesdk() {
     rm -rf ${D}${SDKPATHNATIVE}/var
     # Ensure find-debuginfo is located correctly inside SDK