Re: [Qemu-devel] [PATCH] possible mmap regression

[Edgar E. Iglesias]

On Tue, Feb 12, 2008 at 09:42:15PM +0200, Felipe Contreras wrote:
> Hi,
> 
> I don't know what I'm doing but this seems to fix the weird issue I was 
> having.
> http://article.gmane.org/gmane.comp.emulators.qemu/23314
> 
> I've found out that this happens on linux 2.6.23, but not 2.6.24.
> 
> Cheers.
> 
> -- 
> Felipe Contreras
> diff --git a/linux-user/mmap.c b/linux-user/mmap.c
> index 6292826..3050ad9 100644
> --- a/linux-user/mmap.c
> +++ b/linux-user/mmap.c
> @@ -251,7 +251,7 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int 
> prot,
>             especially important if qemu_host_page_size >
>             qemu_real_host_page_size */
>          p = mmap(g2h(mmap_start),
> -                 host_len, prot, flags | MAP_FIXED, fd, host_offset);
> +                 host_len, prot, flags, fd, host_offset);
>          if (p == MAP_FAILED)
>              return -1;
>          /* update start so that it points to the file position at 'offset' */

Hello,

Sorry, but I beleive your patch will break simulations where the targets 
pagesize is larger than the hosts.

Would you mind trying the attach patched and let us know if it helps for you?
If not, it would be great if you could provide a small test case that trigs the 
bug you are seeing so we can debug the problem.

Best regards
-- 
Edgar E. Iglesias
Axis Communications AB

diff --git a/linux-user/mmap.c b/linux-user/mmap.c
index 6292826..78a8162 100644
--- a/linux-user/mmap.c
+++ b/linux-user/mmap.c
@@ -385,6 +385,9 @@ int target_munmap(abi_ulong start, abi_ulong len)
             real_end -= qemu_host_page_size;
     }
 
+    if (start < mmap_next_start)
+       mmap_next_start = start;
+
     /* unmap what we can */
     if (real_start < real_end) {
         ret = munmap(g2h(real_start), real_end - real_start);