Re: [Qemu-devel] Sigsegv error when create JVM, called by bdrv_create in block.c

[harryxiyou]

On Fri, Feb 8, 2013 at 12:11 AM, Peter Maydell <address@hidden> wrote:
> On 7 February 2013 16:08, Stefan Hajnoczi <address@hidden> wrote:
>> On Thu, Feb 7, 2013 at 3:12 PM, harryxiyou <address@hidden> wrote:
>>> The above debug info show jni will be used in coroutine. I do not
>>> familay with coroutine, however I guess if coroutine not allow to
>>> spawn a new thread? ,or it's stack corrupte with java jvm stack ? ,
>>> For when I modify bdrv_create out of coroutine , it can work - connect
>>> to hdfs without any probleme.
>>
>> Coroutines are allowed to create new threads.
>>
>> Coroutine stacks do not grow automatically but they have 1 MB, which
>> should be enough.
>>
>> There are a number of other things that could be wrong here -
>> missing/incorrect thread synchronization, the shared libraries you are
>> importing messing with the environment (signal masks, signal
>> handlers), etc.
>
> I would suggest that trying to start an entire JVM from within
> QEMU is likely to be brittle at best even if you do get it to
> work, because you've got two big complicated codebases which
> will probably squabble over threads, signal handling, etc etc,
> because they weren't intended to work as part of some other
> large process.
>

Hi：Peter，Stefan
Can I modify block.c , like below ?  - make bdrv_create_co_entry
called out of coroutine ! . Or who can  give me  a elegant way  to
call jni function in coroutine!

/***********************************************************************
int bdrv_create(BlockDriver *drv, const char* filename,
    QEMUOptionParameter *options)
{
    int ret;
    Coroutine *co;
    CreateCo cco = {
        .drv = drv,
        .filename = g_strdup(filename),
        .options = options,
        .ret = NOT_DONE,
    };

    if (!drv->bdrv_create) {
        ret = -ENOTSUP;
        goto out;
    }
#if 1
    bdrv_create_co_entry(&cco);
#else
    if (qemu_in_coroutine()) {
        /* Fast-path if already in coroutine context */
        bdrv_create_co_entry(&cco);
    } else {
        co = qemu_coroutine_create(bdrv_create_co_entry);
        qemu_coroutine_enter(co, &cco);
        while (cco.ret == NOT_DONE) {
            qemu_aio_wait();
        }
    }
#endif
    ret = cco.ret;

out:
    g_free(cco.filename);
    return ret;
}
/*****************************************************************************



-- 
Thanks
Kang Hua