Re: [Qemu-devel] FreeBSD Support

[Leonardo Reiter]

MAP_PRIVATE|MAP_ANON also works on Solaris.  In fact, Linux is the
only platform where it doesn't work due to a bug in the Linux kernel
as Fabrice mentions:

http://www.qemu.org/kqemu-tech.html#SEC7

Technically on Solaris, /tmp is probably the same thing as
MAP_PRIVATE|MAP_ANON since the filesystem is actually mapped to
virtual memory... however, it's much cleaner to not use a file if not
necessary.  I can post a reworked patch that makes the file mapping
for the Linux case only if anyone's interested, but it's a pretty
simple change.

- Leo Reiter

On 2/24/07, Juergen Lock <address@hidden> wrote:
> In article <address@hidden> you write:
> >-=-=-=-=-=-
> >
> >Ok FreeBSD Support round one..
> >
> >Be gentle this is my first attempt at working with the rest of this
> >community..
> >
> >Files it modifies and the reasons are as follows
> >
> >configure - Adds HOST_FREEBSD type to alter included libraries FreeBSD does
> >not need -ltr
> >Makefile.target - Once again uses HOST_FREEBSD to avoid including -ltr
> >
> >osdeps.c - FreeBSD does not have /dev/shm so it uses /tmp for kqemu_valloc
> >also sys/vfs.h is not part of freebsd stat information is part of
> >mount.h/param.h
> >...
>
> Actually the port simply uses mmap MAP_PRIVATE|MAP_ANON, so no
> tempfile is used at all (this is files/patch-osdep.c in the port):
>
> Index: qemu/osdep.c
> @@ -79,7 +79,9 @@
>
>  #if defined(USE_KQEMU)
>
> +#ifndef __FreeBSD__
>  #include <sys/vfs.h>
> +#endif
>  #include <sys/mman.h>
>  #include <fcntl.h>
>
> @@ -90,6 +92,7 @@
>      const char *tmpdir;
>      char phys_ram_file[1024];
>      void *ptr;
> +#ifndef __FreeBSD__
>  #ifdef HOST_SOLARIS
>      struct statvfs stfs;
>  #else
> @@ -151,12 +154,20 @@
>          }
>          unlink(phys_ram_file);
>      }
> +#endif
>      size = (size + 4095) & ~4095;
> +#ifndef __FreeBSD__
>      ftruncate(phys_ram_fd, phys_ram_size + size);
>      ptr = mmap(NULL,
>                 size,
>                 PROT_WRITE | PROT_READ, MAP_SHARED,
>                 phys_ram_fd, phys_ram_size);
> +#else
> +    ptr = mmap(NULL,
> +               size,
> +               PROT_WRITE | PROT_READ, MAP_PRIVATE|MAP_ANON,
> +               -1, 0);
> +#endif
>      if (ptr == MAP_FAILED) {
>          fprintf(stderr, "Could not map physical memory\n");
>          exit(1);
>
>
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