[Qemu-devel] USE_CODE_COPY breaks clone

["Rafael Ávila de Espíndola" <rafael.espindola@ic.unicamp.br>]

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The cvs version of qemu (i386->i386) generates a segmentation fault in the 
emulated code of the attached test program. Commenting the definition of 
USE_CODE_COPY make the test execute successfully.

I think that the problem is in the fact that cpu_init is called in the parent 
process and this functions calls modify_ldt.

Where can I found some documentation about modify_ldt? What is USE_CODE_COPY 
supposed to do?

I will try to call cpu_init from within the new thread and see if it works.

One more question: What do you think about breaking the do_fork function in 
do_fork, do_clone and do_vfork? Presently it tries to guess if it should call 
fork or clone, but do_syscall knows the answer :)

Thanks for any comment,
Rafael

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#include <sched.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

int f(void *oie) {
    printf("%s\n",(char *)oie);
    return 0;
}

int main() {
    const int stack_size = 8192;
    int ret;
    void *buf = malloc(stack_size);
    void *buff_end = buf + stack_size;
    unsigned int flags =CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND;
    char msg[] = "tata";
    ret = clone(f, buff_end, flags, (void *) msg);
    assert(ret != -1);
    printf("blit\n");
    return 0;
}