[dpdk-dev] [PATCH v2] build/ppc: enable build support for Power10

[Thinh Tran <thinhtr@linux.vnet.ibm.com>]

For native build, enabling building the highest cpu_instruction_set
supported by the build host, including the new POWER10.

For cross compile, verifying that the compiler supports the
cpu_instruction_set specified in the cross-file

Signed-off-by: Thinh Tran <thinhtr@linux.vnet.ibm.com>

Reviewed-by: David Christensen <drc@linux.vnet.ibm.com>


v2: 
* resubmit to trigger the rebuild on the current head of repo which
  should have the fix for the build issue reported in Bug 817

---
 config/ppc/meson.build | 83 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 83 insertions(+)

diff --git a/config/ppc/meson.build b/config/ppc/meson.build
index aa1327a595..cba8222163 100644
--- a/config/ppc/meson.build
+++ b/config/ppc/meson.build
@@ -24,6 +24,89 @@ if (cc.get_id() == 'gcc' and cc.version().version_compare('>=10.0') and
         cc.version().version_compare('<12.0') and cc.has_argument('-Wno-psabi'))
     add_project_arguments('-Wno-psabi', language: 'c')
 endif
+# If using a generic build, select the lowest common denominator
+if platform == 'generic'
+     cpu_instruction_set = 'power8'
+# If using a native build, select the highest cpu_instruction_set supported
+# by the build host. (Native is the default platform type set in meson_options.txt.)
+# When a cross compile is detected, verify that the compiler/assembler supports
+# the requested cpu_instruction_set in the cross-file.
+elif platform == 'native'
+    if meson.is_cross_build()
+        # cpu_instruction_set specified in cross-compile file as "cpu"
+        if host_machine.cpu() == 'power10'
+            test_p10 = '''
+#include <stdio.h>
+#include <altivec.h>
+int main() {
+  __vector unsigned __int128 t, a, b;
+#ifdef _ARCH_PWR10
+  __asm__("vcmpequq %0,%1,%2;" : "=v" (t) : "v" (a), "v" (b) : );
+#else
+#error POWER10 not supported
+#endif
+  printf("%d", (int)t[0]);
+  return 0;
+}
+'''
+            if not cc.compiles(test_p10, args : '-mcpu=power10', name: 'Detect P10')
+                  error('POWER10 requested but not supported')
+            endif
+        endif
+    else
+        # Using a POWER native build host. Assume P8 support, move to later CPUs
+        # if supported by the build host and the compiler. Detect the CPU used by
+        # the build host
+        detect_cpu = '''
+#include <stdio.h>
+#include <string.h>
+#include <sys/auxv.h>
+int main() {
+  char * platform = (char*) getauxval(AT_PLATFORM);
+  if (platform) {
+    if (!strncmp(platform,"power",5)) {
+      printf("%s", platform+5); return 0;
+    }
+  }
+  return 1;
+}'''
+        result = cc.run(detect_cpu, name : 'Detect host CPU type')
+        if not result.compiled()
+            error('Failed to detect CPU type')
+        endif
+        cpu = result.stdout().to_int()
+        if cpu < 8
+            error('Unsupported POWER CPU detected')
+        else
+            # Found supported CPU on build host, verify compiler support
+            mcpu_flag = '-mcpu=power@0@'
+            if cc.has_argument(mcpu_flag.format(cpu))
+                # Compiler supports current detected CPU
+            elif cc.has_argument(mcpu_flag.format(cpu-1))
+                cpu = cpu-1
+            elif cc.has_argument(mcpu_flag.format(cpu-2))
+                cpu = cpu-2
+            else
+                error('Compiler does not support POWER@0@ platform'.format(cpu))
+            endif
+            if cpu > 8
+                cpu_instruction_set = 'power'+cpu.to_string()
+            else
+                error('Compiler does not support POWER@0@ platform'.format(cpu))
+            endif
+        endif
+    endif  #end if not cross-build
+else
+    # User has explicitly chosen a platform for the build, use that
+    if cc.has_argument('-mcpu=' + platform)
+        cpu_instruction_set = platform
+    else
+        error('User selected platform ' + platform + ' not supported by compiler')
+    endif
+endif
+machine_args = ['-mcpu=' + cpu_instruction_set, '-mtune=' + cpu_instruction_set]
+dpdk_conf.set('RTE_MACHINE', cpu_instruction_set)
+
 
 # Certain POWER9 systems can scale as high as 1536 LCORES, but setting such a
 # high value can waste memory, cause timeouts in time limited autotests, and is
-- 
2.25.1