Re: [PATCH v6] lib/eal/ppc fix compilation for musl

[David Marchand]

On Sat, May 7, 2022 at 11:16 PM Duncan Bellamy <d...@denkimushi.com> wrote:
>
> musl lacks __ppc_get_timebase() but has __builtin_ppc_get_timebase()
>
> the __ppc_get_timebase_freq() is taken from:
> https://git.alpinelinux.org/aports/commit/?id=06b03f70fb94972286c0c9f6278df89e53903833
>
> Signed-off-by: Duncan Bellamy <d...@denkimushi.com>

- A patch title does not need lib/ prefix.
Here, "eal/ppc: " is enough.


- Code in lib/eal/linux won't be used for FreeBSD/Windows.
On the other hand, arch-specific code (here, lib/eal/ppc/) can be used
for the various OS.
Besides, as far as I can see in the Linux kernel sources, powerpc is
the only architecture that exports a "timebase" entry in
/proc/cpuinfo.
So, I see no reason to put any code out of lib/eal/ppc.


- In the end, unless I missed some point, the patch could probably
look like (untested):

diff --git a/lib/eal/ppc/include/rte_cycles.h b/lib/eal/ppc/include/rte_cycles.h
index 5585f9273c..666fc9b0bf 100644
--- a/lib/eal/ppc/include/rte_cycles.h
+++ b/lib/eal/ppc/include/rte_cycles.h
@@ -10,7 +10,10 @@
 extern "C" {
 #endif

+#include <features.h>
+#ifdef __GLIBC__
 #include <sys/platform/ppc.h>
+#endif

 #include "generic/rte_cycles.h"

@@ -26,7 +29,11 @@ extern "C" {
 static inline uint64_t
 rte_rdtsc(void)
 {
+#ifdef __GLIBC__
        return __ppc_get_timebase();
+#else
+       return __builtin_ppc_get_timebase();
+#endif
 }

 static inline uint64_t
diff --git a/lib/eal/ppc/rte_cycles.c b/lib/eal/ppc/rte_cycles.c
index 3180adb0ff..99d36b2f7e 100644
--- a/lib/eal/ppc/rte_cycles.c
+++ b/lib/eal/ppc/rte_cycles.c
@@ -2,12 +2,50 @@
  * Copyright (C) IBM Corporation 2019.
  */

+#include <features.h>
+#ifdef __GLIBC__
 #include <sys/platform/ppc.h>
+#elif RTE_EXEC_ENV_LINUX
+#include <string.h>
+#include <stdio.h>
+#endif

 #include "eal_private.h"

 uint64_t
 get_tsc_freq_arch(void)
 {
+#ifdef __GLIBC__
        return __ppc_get_timebase_freq();
+#elif RTE_EXEC_ENV_LINUX
+       static unsigned long base;
+       char buf[512];
+       ssize_t nr;
+       FILE *f;
+
+       if (base != 0)
+               goto out;
+
+       f = fopen("/proc/cpuinfo", "rb");
+       if (f == NULL)
+               goto out;
+
+       while (fgets(buf, sizeof(buf), f) != NULL) {
+               char *ret = strstr(buf, "timebase");
+
+               if (ret == NULL)
+                       continue;
+               ret += sizeof("timebase") - 1;
+               ret = strchr(ret, ':');
+               if (ret == NULL)
+                       continue;
+               base = strtoul(ret + 1, NULL, 10);
+               break;
+       }
+       fclose(f);
+out:
+       return (uint64_t) base;
+#else
+       return 0;
+#endif
 }


-- 
David Marchand