Re: [Qemu-devel] dynamically linked binaries under sparc-linux-user

[Artyom Tarasenko <atar4qemu@gmail.com>]

On Thu, May 26, 2011 at 8:45 PM, Blue Swirl <blauwirbel@gmail.com> wrote:
> On Tue, May 24, 2011 at 10:42 PM, Artyom Tarasenko <atar4qemu@gmail.com> wrote:
>> Should it be possible to use dynamically linked binaries under
>> sparc*-linux-user?
>> Under qemu-system-sparc the Debian 4.08r1 initrd works fine, but:
>>
>> master$ sparc-linux-user/qemu-sparc -strace -L
>> ../debian-4.08r1-initrd/ ../debian-4.08r1-initrd/bin/busybox
>> 14004 uname(0x409ffbae) = 0
>> 14004 brk(NULL) = 0x00063000
>> 14004 access("/etc/ld.so.nohwcap",F_OK) = -1 errno=2 (No such file or directory)
>> 14004 mmap(NULL,4096,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANONYMOUS,-1,0)
>> = 0x40a2c000
>> 14004 access("/etc/ld.so.preload",R_OK) = -1 errno=2 (No such file or directory)
>> 14004 open("/etc/ld.so.cache",O_RDONLY) = 3
>> 14004 fstat64(3,0x409ff500) = 0
>> 14004 mmap(NULL,195479,PROT_READ,MAP_PRIVATE,3,0) = 0x40a2d000
>> 14004 close(3) = 0
>> Segmentation fault
>>
>> The strange thing here is that it loads ld.so.cache. The guest fs
>> doesn't have it, but the host does:
>>
>> master$  ll ../../debian-4.08r1-initrd/etc/ld.so.cache /etc/ld.so.cache
>> ls: cannot access ../../debian-4.08r1-initrd/etc/ld.so.cache: No such
>> file or directory
>> -rw-r--r--. 1 root root 195479 2011-03-17 13:48 /etc/ld.so.cache
>>
>> Isn't this wrong?
>
> I'm not sure.

Right. On a second thought, qemu is probably doing what is expected:
the syscalls are emulated, so the host libraries must be loaded.
Then the problem must be elsewhere. Here is the backtrace:

master$  gdb sparc-linux-user/qemu-sparc
GNU gdb (GDB) Fedora (7.0.1-50.fc12)
(gdb) run -L ../debian-4.08r1-initrd/ ../debian-4.08r1-initrd/bin/busybox
Starting program: sparc-linux-user/qemu-sparc -L
../debian-4.08r1-initrd/ ../debian-4.08r1-initrd/bin/busybox
[Thread debugging using libthread_db enabled]

Program received signal SIGSEGV, Segmentation fault.
0x00000000601c49c2 in static_code_gen_buffer ()
Missing separate debuginfos, use: debuginfo-install
glibc-2.11.2-3.x86_64 libattr-2.4.44-1.fc12.x86_64
nspr-4.8.6-1.fc12.x86_64 nss-3.12.8-2.fc12.x86_64
nss-util-3.12.8-1.fc12.x86_64 zlib-1.2.3-23.fc12.x86_64
(gdb) bt
#0  0x00000000601c49c2 in static_code_gen_buffer ()
#1  0x00007fffffffd684 in ?? ()
#2  0x00007ffff4bc8728 in ?? ()
#3  0x00000000ffffffff in ?? ()
#4  0x0000000060029083 in tb_alloc_page (tb=0x40a2bc00, phys_pc=<value
optimized out>, phys_page2=1084406920) at exec.c:1214
#5  tb_link_page (tb=0x40a2bc00, phys_pc=<value optimized out>,
phys_page2=1084406920) at exec.c:1278
#6  0x000000006002a037 in tb_gen_code (env=0x6223f390, pc=1084305880,
cs_base=<value optimized out>, flags=<value optimized out>,
cflags=<value optimized out>)
    at exec.c:1004
#7  0x000000006002afe8 in cpu_sparc_exec (env1=<value optimized out>)
at cpu-exec.c:636
#8  0x0000000060005d50 in cpu_loop (env=0x6223f390) at linux-user/main.c:1008
#9  0x00000000600069d9 in main (argc=1646342192, argv=<value optimized
out>, envp=<value optimized out>) at linux-user/main.c:3533
(gdb)

Any ideas?

> It could be possible to construct a blacklist of host
> files that may not be accessible or visible to the guest but that
> wouldn't very robust either. Chrooting into a 100% guest architecture
> system should work better.

You mean some sort of mixed chrooting? At least some host libraries
must be visible to the guest as if they were native.

-- 
Regards,
Artyom Tarasenko

solaris/sparc under qemu blog: http://tyom.blogspot.com/