[PATCH v2] Xen: Update compiler checks

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

We have checks in both xen/compiler.h, and Config.mk.  Both are incomplete.
Remove the one from compiler.h, as it's pointless to perform in addition to
the xen.git-wide one as well.

Expand the checks to cover RISCV wanting GCC 11.1, and to cover Clang on x86.

PPC still is unspecified, and inherits the GCC 5.1 global baseline.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Anthony PERARD <anthony.perard@xxxxxxxxxx>
CC: Michal Orzel <michal.orzel@xxxxxxx>
CC: Jan Beulich <jbeulich@xxxxxxxx>
CC: Julien Grall <julien@xxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
CC: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>

v2:
 * Change to altering Config.mk

https://gitlab.com/xen-project/people/andyhhp/xen/-/pipelines/1738628602 with
the CI changes reverted, so as to expect failures for CentOS 7 and earlier
Ubuntu Clangs.

The $(eval $(check-y)) is badly positioned:

  xen.git/xen$ make
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
    HOSTCC  tools/fixdep
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  make[1]: *** [scripts/Makefile.host:108: tools/fixdep] Error 1
    HOSTCC  tools/symbols
  *** FATAL BUILD ERROR: Xen requires at least GCC 0x150100
  make[1]: *** [scripts/Makefile.host:108: tools/symbols] Error 1
  make: *** [Makefile:610: xen] Error 2

It is involved every time Config.mk is included, rather than once per `make`
invocation.
---
 Config.mk                  | 14 ++++++++++++--
 xen/include/xen/compiler.h | 14 --------------
 2 files changed, 12 insertions(+), 16 deletions(-)

diff --git a/Config.mk b/Config.mk
index 8a73f3da62b4..a9d62fc10cfa 100644
--- a/Config.mk
+++ b/Config.mk
@@ -125,8 +125,18 @@ define cc-ver-check-closure
     endif
 endef
 
-# Require GCC v4.1+
-check-$(gcc) = $(call cc-ver-check,CC,0x040100,"Xen requires at least gcc-4.1")
+# Minimum GCC version: 5.1, except for RISCV which needs 11.1
+ifeq ($(XEN_TARGET_ARCH),riscv64)
+check-$(gcc) = $(call cc-ver-check,CC,0x110100,"Xen requires at least GCC 
11.1")
+else
+check-$(gcc) = $(call cc-ver-check,CC,0x050100,"Xen requires at least GCC 5.1")
+endif
+
+# Minimum Clang version: 11, x86 only
+ifeq ($(XEN_TARGET_ARCH),x86_64)
+check-$(clang) = $(call cc-ver-check,CC,0x110000,"Xen requires at least Clang 
11")
+endif
+
 $(eval $(check-y))
 
 ld-ver-build-id = $(shell $(1) --build-id 2>&1 | \
diff --git a/xen/include/xen/compiler.h b/xen/include/xen/compiler.h
index 636a85bc417d..43b666133a92 100644
--- a/xen/include/xen/compiler.h
+++ b/xen/include/xen/compiler.h
@@ -1,20 +1,6 @@
 #ifndef __LINUX_COMPILER_H
 #define __LINUX_COMPILER_H
 
-#if !defined(__GNUC__) || (__GNUC__ < 4)
-#error Sorry, your compiler is too old/not recognized.
-#elif CONFIG_CC_IS_GCC
-# if defined(CONFIG_ARM_32) && CONFIG_GCC_VERSION < 40900
-#  error Sorry, your version of GCC is too old - please use 4.9 or newer.
-# elif defined(CONFIG_ARM_64) && CONFIG_GCC_VERSION < 50100
-/*
- * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63293
- * https://lore.kernel.org/r/20210107111841.GN1551@xxxxxxxxxxxxxxxxxxxxx
- */
-#  error Sorry, your version of GCC is too old - please use 5.1 or newer.
-# endif
-#endif
-
 #ifdef CONFIG_CC_HAS_VISIBILITY_ATTRIBUTE
 /* Results in more efficient PIC code (no indirections through GOT or PLT). */
 #pragma GCC visibility push(hidden)
-- 
2.39.5