[xen stable-4.17] build: define ARCH and SRCARCH later

[patchbot@xxxxxxx]

commit 1c3927f8f6743538a35aa45a91a2d4adbde9f277
Author:     Anthony PERARD <anthony.perard@xxxxxxxxxx>
AuthorDate: Wed Jul 5 08:25:03 2023 +0200
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Tue Aug 22 13:43:05 2023 +0100

    build: define ARCH and SRCARCH later
    
    Defining ARCH and SRCARCH later in xen/Makefile allows to switch to
    immediate evaluation variable type.
    
    ARCH and SRCARCH depend on value defined in Config.mk and aren't used
    for e.g. TARGET_SUBARCH or TARGET_ARCH, and not before they're needed in
    a sub-make or a rule.
    
    This will help reduce the number of times the shell rune is been
    run.
    
    With GNU make 4.4, the number of execution of the command present in
    these $(shell ) increased greatly. This is probably because as of make
    4.4, exported variable are also added to the environment of $(shell )
    construct.
    
    Also, `make -d` shows a lot of these:
        Makefile:39: not recursively expanding SRCARCH to export to shell 
function
        Makefile:38: not recursively expanding ARCH to export to shell function
    
    Reported-by: Jason Andryuk <jandryuk@xxxxxxxxx>
    Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
    Tested-by: Jason Andryuk <jandryuk@xxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    (cherry picked from commit 58e0a3f3b2c430f8640ef9df67ac857b0008ebc8)
---
 xen/Makefile | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/xen/Makefile b/xen/Makefile
index f6005bd536..7ecfa6e8e9 100644
--- a/xen/Makefile
+++ b/xen/Makefile
@@ -35,12 +35,6 @@ MAKEFLAGS += -rR
 
 EFI_MOUNTPOINT ?= $(BOOT_DIR)/efi
 
-ARCH=$(XEN_TARGET_ARCH)
-SRCARCH=$(shell echo $(ARCH) | \
-          sed -e 's/x86.*/x86/' -e s'/arm\(32\|64\)/arm/g' \
-              -e s'/riscv.*/riscv/g')
-export ARCH SRCARCH
-
 # Allow someone to change their config file
 export KCONFIG_CONFIG ?= .config
 
@@ -241,6 +235,13 @@ include scripts/Kbuild.include
 include $(XEN_ROOT)/Config.mk
 
 # Set ARCH/SUBARCH appropriately.
+
+ARCH := $(XEN_TARGET_ARCH)
+SRCARCH := $(shell echo $(ARCH) | \
+    sed -e 's/x86.*/x86/' -e 's/arm\(32\|64\)/arm/g' \
+        -e 's/riscv.*/riscv/g')
+export ARCH SRCARCH
+
 export TARGET_SUBARCH  := $(XEN_TARGET_ARCH)
 export TARGET_ARCH     := $(shell echo $(XEN_TARGET_ARCH) | \
                             sed -e 's/x86.*/x86/' -e s'/arm\(32\|64\)/arm/g' \
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.17