Hi Jiayuan,
I'm not completely sure, it really depends on what you're new thread
code is doing. From a simulation stand point all M5 is doing is
providing an implementation of the brk() syscall. If malloc()
increases the break size, physical frames are allocated and mapped
the virtual addresses between the old brk and the new one
(syscall_emul.cc:110). I can't see how this would be a problem, but
no guarantees. My guess would be something to do with malloc() not
expecting a threaded process.
Ali
On Jun 12, 2007, at 11:26 PM, Jiayuan Meng wrote:
Hi Ali,
Thanks for the hint and I did find that there is an error. But I'm
not sure whether it's the problem with my implementation or with M5.
Here is the problem:
void thread_main()
{
int* x = new x[10];
delete [] x;
my_exit(); // inlined assembly(asm volatile (".byte 0x61,
0x00,0x00,0x40))
}
main()
{
for(int n=0; n<4; n++)
thread_create(&thread_main); // inlined assembly(asm
volatile (".byte 0x62, 0x00,0x00,0x40))
wait(); // inlined assembly(asm volatile (".byte 0x63,
0x00,0x00,0x40))
}
in the following example, I am trying to create 4 threads running
simultaneously. Each of the thread allocate some heap space and
then free it.
I am expecting that the "x"s in each thread is assigned to a
different address in the heap. But I found that the 4 threads
allocate exactly the same address to the 4 "x"s, thus, when they
try to free "x", it is freed four times and the application invokes
an error:
*** glibc detected *** double free or corruption (fasttop):
0x00000001201d8a40 ***
and this error is always followed by the "stat64 unimplemented"
message.
Can you also give me some hints about how to solve this? why does
the four threads assign their "x" the same address? how can I get
around with this?
Thanks!
Jiayuan
----- Original Message -----
From: Ali Saidi
To: M5 users mailing list
Sent: 2007年6月13日 10:24 AM
Subject: Re: [m5-users] thread alloc/dealloc error and stat64
system call
I'm not sure I know why stat64 is being called. It could be that
one of your new instructions isn't what you think it is and the
program execution path changes to some error handler, or something
else. You probably want to create an instruction trace and make
sure it's doing what you think it is. If that is the case then
implementing stat64 shouldn't be that difficult, just take a look
at fstat64. stat64 is the same thing but instead of argument 1
being a file descriptor it's a path to a file.
Ali
On Jun 12, 2007, at 8:14 PM, Jiayuan Meng wrote:
Hi all,
As I am trying to run a thread in SE mode, I made up the following
code:
void thread_main()
{
int* x = new x[10];
delete [] x;
my_exit(); // inlined assembly(asm volatile (".byte 0x61,
0x00,0x00,0x40))
}
main()
{
launch(&thread_main); // inlined assembly(asm volatile (".byte
0x62, 0x00,0x00,0x40))
wait(); // inlined assembly(asm volatile (".byte 0x63,
0x00,0x00,0x40))
}
To launch this thread, what I did was: allocate a stack, assign
the pc, and activate the thread context on another cpu. my_exit()
will tell the simulator that this thread is finished and the
simulator will deallocate/halt its thread context.
The extened assemblies are implemented following the M5FUNC pseudo
instructions.
I use crosstool's g++ 3.4.3 to compile the code to alpha-linux. M5
is compiled on a 64bit x86 machine.
I get the following message:
fatal: syscall stat64 (#425) unimplemented.
how ever, if I just change the thread_main to:
void thread_main()
{
int* x = new x
delete x;
my_exit();
}
The error will be gone. What can I do to allow the first case to
work? is there any patch for system call stat64?
Thanks!
Jiayuan
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