[Qemu-devel] qemu-arm fails on test-mmap - take #2

["Jan-Simon Möller" <dl9pf@gmx.de>]

Hi !

This is a follow-up to my tests about test-mmap failing inside an arm chroot 
when using qemu-arm in user-mode.

Here are 2 snippets running   "qemu-arm ./test-mmap"  outside and inside the 
ARM chroot env.

I turned DEBUG_MMAP on in linux-user/mmap.c .

legolas:/var/tmp/build-root # ./usr/bin/qemu-arm test-mmap
------snip-------
mmap: start=0x00000000 len=0x00001000 prot=r-- flags=MAP_ANON MAP_PRIVATE 
fd=-1 offset=00000000
ret=0x40b77000
start    end      size     prot
00008000-00081000 00079000 r-x
00088000-0008a000 00002000 rw-
0008a000-0008c000 00002000 rwx
0008c000-000af000 00023000 rw-
40000000-40080000 00080000 rw-
40080000-40081000 00001000 ---
40081000-40082000 00001000 rw-
40339000-40347000 0000e000 ---
407d6000-407d7000 00001000 ---
4096b000-40974000 00009000 ---
40b76000-40b78000 00002000 r--
40e8a000-40e8c000 00002000 ---
41dc7000-455ca000 03803000 ---
60000000-60166000 00166000 ---
60266000-6231d000 020b7000 ---
------snip-------

Note the last 2 lines !!

Now same procedure inside the chroot ...
legolas:/> chroot /var/tmp/build-root
legolas:/> ./test-mmap

------snip-------
mmap: start=0x00000000 len=0x00001000 prot=r-- flags=MAP_ANON MAP_PRIVATE 
fd=-1 offset=00000000
ret=0x40b74000
start    end      size     prot
00008000-00081000 00079000 r-x
00088000-0008a000 00002000 rw-
0008a000-0008c000 00002000 rwx
0008c000-000af000 00023000 rw-
40000000-40080000 00080000 rw-
40080000-40081000 00001000 ---
40081000-40082000 00001000 rw-
40191000-40192000 00001000 ---
40b73000-40b75000 00002000 r--
40c6c000-40c75000 00009000 ---
41105000-41106000 00001000 ---
41283000-44a95000 03812000 ---
------snip-------


The lines with 60000000-60166000 are gone ... 
Thus as soon as those pages will get allocated  it will segfault.

This is reproducible on different machines:
1)
openSUSE 11.1 64bit on Core 2 Duo  with 2GB Ram, qemu git head
The ARM chroot uses gcc4.4 and glibc 2.10.1 .

2)
openSUSE 11.0 32bit  Athlon XP 2GB RAM, same qemu, same chroot


Now my question is: how is the data of the already blocked pages 
processed/aquired ? It seems to me that the pages get "lost" somewhere.


Best,
Jan-Simon