Re: [uml-devel] Re: uml-patch-2.6.0

[Jeff Dike <jdike@addtoit.com>]

mingo@elte.hu said:
> unfortunately, this is only the case if the kernel is below 2.5.69 and
> has 'nptl' in the uname. Otherwise ld.so assumes full NPTL support.

So, it uses uname to figure out if the kernel has NPTL support?

> so the only compatible solution seems to be to implement set/
> get_thread_area() within UML. Since UML itself is linked statically,
> which causes the non-TLS glibc to be linked, i think it should be safe
> to just shadow the TLS descriptors in the UML process and call
> set_thread_area() for every new thread that has TLS descriptors not
> equal to the previous thread's TLS descriptors.

In tt mode, this is true.  A skas-only UML will be dynamic, but then
userspace is in a separate process, and someone was thoughtful enough to
add PTRACE_[GS]ET_THREAD_INFO.  So, this will be fine in either case.

The problem is on 2.4.  I suspect that this can't be emulated on 2.4 hosts,
so a 2.6 UML can't boot a NPTL system on a 2.4 host.  This is annoying since
host version independence is a nice thing about UML.

> but wrt. LinuxThreads - it doesnt seem UML skas mode implements LDT
> state properly - does it? 

As far as I know, it does.  LinuxThreads was introduced in RH8 or so, I think,
and RH8 filesystems have run in UML for a long time.

				Jeff



-------------------------------------------------------
The SF.Net email is sponsored by EclipseCon 2004
Premiere Conference on Open Tools Development and Integration
See the breadth of Eclipse activity. February 3-5 in Anaheim, CA.
http://www.eclipsecon.org/osdn
_______________________________________________
User-mode-linux-devel mailing list
User-mode-linux-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel