Re: [Qemu-devel] [PATCH v2] qemu_mutex_iothread_locked not correctly synchronized

[Stefan Weil <sw@weilnetz.de>]

Am 26.11.2015 um 10:12 schrieb David Engraf:
> Am 25.11.2015 um 17:16 schrieb Paolo Bonzini:
>>
>>
>> On 25/11/2015 16:48, David Engraf wrote:
>>>
>>> Indeed, TLS handling is broken. The address of iothread_locked is
>>> always
>>> the same between threads and I can see that a different thread sets
>>> iothread_locked to false, thus my current thread uses an invalid state.
>>> I will have to check why my compiler produces invalid TLS code.
>>
>> That rings a bell, I think there are different CRT libraries or
>> something like that.  Stefan, what would break TLS under Windows?
>
> "--extra-cflags=-mthreads" is the solution. iothread_locked is unique
> for each thread now. I saw that this is already mentioned in the
> Documentation [1], but why isn't that enabled by default if QEMU
> requires this option on Windows? Without this option, even the latest
> version of gcc doesn't produce working TLS code.
>
> Many thanks for your support!
>
> David
>
> [1] http://wiki.qemu.org/Hosts/W32

Hi David,

I just prepared a patch which will enable that option by default
for all compilations targeting Windows.

Thanks for your report!

Regards,
Stefan