Re: [Qemu-devel] [PATCH] no mmap for alsa

[Alexander Graf <agraf@suse.de>]

[-- Attachment #1: Type: text/plain, Size: 68 bytes --]

Oops, the patch did not compile. This is the updated version.

Alex

[-- Attachment #2: alsa_mmap --]
[-- Type: text/plain, Size: 1134 bytes --]

Index: qemu/linux-user/mmap.c
===================================================================
--- qemu.orig/linux-user/mmap.c
+++ qemu/linux-user/mmap.c
@@ -152,6 +152,9 @@ static int mmap_frag(target_ulong real_s
     return 0;
 }
 
+#define SNDRV_PCM_MMAP_OFFSET_STATUS  0x80000000
+#define SNDRV_PCM_MMAP_OFFSET_CONTROL 0x81000000
+
 /* NOTE: all the constants are the HOST ones */
 long target_mmap(target_ulong start, target_ulong len, int prot, 
                  int flags, int fd, target_ulong offset)
@@ -192,6 +195,17 @@ long target_mmap(target_ulong start, tar
     }
 #endif
 
+    /* Alsa tries to communcate with the kernel via mmap. This usually
+     * is a good idea when user- and kernelspace are running on the 
+     * same architecture but does not work out when not. To make alsa
+     * not to use mmap, we can just have it fail on the mmap calls that
+     * would initiate this.
+     */
+    if(offset == SNDRV_PCM_MMAP_OFFSET_STATUS || offset == SNDRV_PCM_MMAP_OFFSET_CONTROL) {
+	errno = EINVAL;
+	return -1;
+    }
+
     if (offset & ~TARGET_PAGE_MASK) {
         errno = EINVAL;
         return -1;