Re: Generic way to detect qemu linux-user emulation

[Peter Maydell <peter.maydell@linaro.org>]

On Tue, 18 Mar 2025 at 15:04, Peter Maydell <peter.maydell@linaro.org> wrote:
> More generally, AIUI glibc expects that it has control over what's
> happening with threads, so it can set up its own data structures
> for the new thread (e.g. for TLS variables). This email from the
> glibc mailing list is admittedly now two decades old
> https://public-inbox.org/libc-alpha/200408042007.i74K7ZOr025380@magilla.sf.frob.com/
> but it says:
>
> # Basically, if you want to call libc functions you should do it from a
> # thread that was set up by libc or libpthread.  i.e., if you make your own
> # threads with clone, only call libc functions from the initial thread.

I spoke to some glibc devs on IRC and they confirmed that this
remains true for modern glibc: because glibc needs to set up
things like TLS on new threads, you can't mix your own direct
calls to clone() with calls to glibc functions.

-- PMM