[Qemu-devel] [PATCH] RFC: Read the cache information from /proc/self/auxv on PPC Linux

[Qemu-devel] [PATCH] RFC: Read the cache information from /proc/self/auxv on PPC Linux

[Filip Navara]

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Hello,

I'd really like to cleanup the code for SDL_main, but a prerequisite
is to change reading of cache information on PPC Linux. This patch is
based on suggestion by Hollis Blanchard. If ppc_init_cacheline_sizes
gets fixed on PPC Linux we will no longer need to pass the "env"
variable around and the code will be cleaner. Unfortunately I don't
have access to PPC Linux, so I can't really test if the patch works or
even compiles, so any help is appreciated.

Thanks,
Filip Navara

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From ac63e41830ec555a36e05bd37c9718945b3c8e3b Mon Sep 17 00:00:00 2001
From: Filip Navara <filip.navara@gmail.com>
Date: Tue, 23 Jun 2009 16:47:24 +0200
Subject: [PATCH] Read the cache information from /proc/self/auxv on PPC Linux

---
 cache-utils.c |   24 +++++++++++++++---------
 1 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/cache-utils.c b/cache-utils.c
index 45d62c9..1675905 100644
--- a/cache-utils.c
+++ b/cache-utils.c
@@ -16,6 +16,8 @@ static void ppc_init_cacheline_sizes(void)
 }
 
 #elif defined __linux__
+#include <unistd.h>
+#include <fcntl.h>
 
 #define QEMU_AT_NULL        0
 #define QEMU_AT_DCACHEBSIZE 19
@@ -23,16 +25,20 @@ static void ppc_init_cacheline_sizes(void)
 
 static void ppc_init_cacheline_sizes(char **envp)
 {
-    unsigned long *auxv;
-
-    while (*envp++);
-
-    for (auxv = (unsigned long *) envp; *auxv != QEMU_AT_NULL; auxv += 2) {
-        switch (*auxv) {
-        case QEMU_AT_DCACHEBSIZE: qemu_cache_conf.dcache_bsize = auxv[1]; break;
-        case QEMU_AT_ICACHEBSIZE: qemu_cache_conf.icache_bsize = auxv[1]; break;
-        default: break;
+    int fd;
+    unsigned long auxv[2];
+    
+    fd = open("/proc/self/auxv", O_RDONLY);
+    if (fd != -1) {
+        while (read(fd, auxv, sizeof(auxv)) == sizeof(auxv) &&
+               auxv[0] != QEMU_AT_NULL) {
+            switch (auxv[0]) {
+            case QEMU_AT_DCACHEBSIZE: qemu_cache_conf.dcache_bsize = auxv[1]; break;
+            case QEMU_AT_ICACHEBSIZE: qemu_cache_conf.icache_bsize = auxv[1]; break;
+            default: break;
+            }
         }
+        close(fd);
     }
 }
 
-- 
1.6.3.msysgit.0

Re: [Qemu-devel] [PATCH] RFC: Read the cache information from /proc/self/auxv on PPC Linux

[malc]

On Tue, 23 Jun 2009, Filip Navara wrote:

> Hello,
> 
> I'd really like to cleanup the code for SDL_main, but a prerequisite
> is to change reading of cache information on PPC Linux. This patch is
> based on suggestion by Hollis Blanchard. If ppc_init_cacheline_sizes
> gets fixed on PPC Linux we will no longer need to pass the "env"
> variable around and the code will be cleaner. Unfortunately I don't
> have access to PPC Linux, so I can't really test if the patch works or
> even compiles, so any help is appreciated.

That will only work on 2.6 and only when proc is mounted.

-- 
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