22 Sep
2015
22 Sep
'15
3:38 p.m.
Hello,
I'm trying to build uClibc-based userspace for uclinux. It builds
and works as long as I keep uClibc single-threaded. If I enable
TLS and NPTL support first I face build errors (one caused by
reference to fork from libpthread/nptl/sysdeps/unix/sysv/linux/fork.c,
other outside uClibc, in the elf2flt, which cannot deal with .tbss
section overlapping .data section) and then runtime errors
(an attempt to allocate TLS memory with sbrk which doesn't
work in uclinux and then inability to initialize TLS data, which I
haven't tracked yet). All that makes me think that either I'm doing
something terribly wrong, or TLS + NPTL are not supported by
uClibc for uclinux.
So my questions are:
- are TLS and NPTL supported by uClibc for uclinux?
- if not, what are the supported threading options?
--
Thanks.
-- Max
22 Sep
22 Sep
4:10 p.m.
Hello Max,
On Tue, 22 Sep 2015 18:38:06 +0300
Max Filippov <jcmvbkbc(a)gmail.com> wrote:
Hello,
I'm trying to build uClibc-based userspace for uclinux. It builds
and works as long as I keep uClibc single-threaded. If I enable
TLS and NPTL support first I face build errors (one caused by
reference to fork from libpthread/nptl/sysdeps/unix/sysv/linux/fork.c,
other outside uClibc, in the elf2flt, which cannot deal with .tbss
section overlapping .data section) and then runtime errors
(an attempt to allocate TLS memory with sbrk which doesn't
work in uclinux and then inability to initialize TLS data, which I
haven't tracked yet). All that makes me think that either I'm doing
something terribly wrong, or TLS + NPTL are not supported by
uClibc for uclinux.
So my questions are:
- are TLS and NPTL supported by uClibc for uclinux?
- if not, what are the supported threading options?
Try linuxthreads.old, it works for us (0.9.33.2, Cortex-M3/M4. Toolchain is an old
CodeSourcery arm-uclinuxeabi arm-2010q1).
Regards,
Sergei
6:55 p.m.
Sergei,
On Tue, Sep 22, 2015 at 7:10 PM, Sergei Poselenov
<sposelenov(a)emcraft.com> wrote:
On Tue, 22 Sep 2015 18:38:06 +0300
Max Filippov <jcmvbkbc(a)gmail.com> wrote:
Ok, I was able to build uClibc with linuxthreads.old and it
works. Thank you!
I'm a bit concerned about the toolchain that it compiled
source with TLS variables without a single warning, but
the variables weren't actually thread-local. Oh, well...
--
Thanks.
-- Max
So my questions are:
- are TLS and NPTL supported by uClibc for uclinux?
- if not, what are the supported threading options?
Try linuxthreads.old, it works for us (0.9.33.2, Cortex-M3/M4. Toolchain is an old
CodeSourcery arm-uclinuxeabi arm-2010q1).
7:04 p.m.
Max,
On Tue, 2015-09-22 at 21:55 +0300, Max Filippov wrote:
Sergei,
On Tue, Sep 22, 2015 at 7:10 PM, Sergei Poselenov
<sposelenov(a)emcraft.com> wrote:
Just for my information - what is your hardware platform and what
toolchain combo you tried to build?
Regards,
Sergei
On Tue, 22 Sep 2015 18:38:06 +0300
Max Filippov <jcmvbkbc(a)gmail.com> wrote:
Ok, I was able to build uClibc with linuxthreads.old and it
works. Thank you!
I'm a bit concerned about the toolchain that it compiled
source with TLS variables without a single warning, but
the variables weren't actually thread-local. Oh, well...
So my questions are:
- are TLS and NPTL supported by uClibc for uclinux?
- if not, what are the supported threading options?
Try linuxthreads.old, it works for us (0.9.33.2, Cortex-M3/M4. Toolchain is an old
CodeSourcery arm-uclinuxeabi arm-2010q1).
7:12 p.m.
On Tue, Sep 22, 2015 at 10:04 PM, Sergei Poselenov
<sposelenov(a)emcraft.com> wrote:
Max,
On Tue, 2015-09-22 at 21:55 +0300, Max Filippov wrote:
It's xtensa, binutils-2.24, gcc-5.2.0, uClibc snapshot at
revision 7bf35c8b7d4a1f97174eb49f47f33946b282114c all built
with the buildroot-2015.08, with corresponding patches.
I also had to revert the patch that dropped xtensa-specific
uClibc snapshot, otherwise there's only uClibc-ng which
doesn't offer linuxthreads.old support for xtensa.
--
Thanks.
-- Max
Sergei,
On Tue, Sep 22, 2015 at 7:10 PM, Sergei Poselenov
<sposelenov(a)emcraft.com> wrote:
Just for my information - what is your hardware platform and what
toolchain combo you tried to build? On Tue, 22 Sep 2015 18:38:06 +0300
Max Filippov <jcmvbkbc(a)gmail.com> wrote:
Ok, I was able to build uClibc with linuxthreads.old and it
works. Thank you!
I'm a bit concerned about the toolchain that it compiled
source with TLS variables without a single warning, but
the variables weren't actually thread-local. Oh, well...
So my questions are:
- are TLS and NPTL supported by uClibc for uclinux?
- if not, what are the supported threading options?
Try linuxthreads.old, it works for us (0.9.33.2, Cortex-M3/M4. Toolchain is an old
CodeSourcery arm-uclinuxeabi arm-2010q1). 
4:25 p.m.
On Tue, Sep 22, 2015 at 06:38:06PM +0300, Max Filippov wrote:
Hello,
I'm trying to build uClibc-based userspace for uclinux. It builds
and works as long as I keep uClibc single-threaded. If I enable
TLS and NPTL support first I face build errors (one caused by
reference to fork from libpthread/nptl/sysdeps/unix/sysv/linux/fork.c,
other outside uClibc, in the elf2flt, which cannot deal with .tbss
section overlapping .data section) and then runtime errors
(an attempt to allocate TLS memory with sbrk which doesn't
work in uclinux and then inability to initialize TLS data, which I
haven't tracked yet). All that makes me think that either I'm doing
something terribly wrong, or TLS + NPTL are not supported by
uClibc for uclinux.
As far as I can tell, the bFLT format and linker scripts used have no
way to represent the location/size of the TLS image, so inability to
initialize TLS makes sense. I think this could be solved by having the
linker script put symbols around the TLS image and referencing the
symbols rather than ELF headers to find it. Of course dropping bFLT
and using FDPIC or regular ELF would be the ideal solution.
I've looked at this all recently; see this and the containing thread:
http://lists.nommu.org/pipermail/nommu/2015-September/000037.html
So my questions are:
- are TLS and NPTL supported by uClibc for uclinux?
- if not, what are the supported threading options?
At this point, I think the answer is no, and it would probably be
considerable work to get it working. Nothing that's prohibitively
difficult for someone familiar with the code and linking/binfmt
topics, but still time-consuming.
The old LinuxThreads may or may not work (for some limited definition
of "work") on some NOMMU targets. It probably varies from one to
another so I don't think there's a single answer to your second
question without knowing which target(s) you care about.
What I would recommend if you need threads/TLS, but I'm naturally
biased: I'm presently working on FDPIC-based NOMMU support in musl
libc with thread and TLS support matching normal targets with MMU.
It's already mostly working and progressing rapidly, but the only
supported target so far is SH. Getting more NOMMU targets added would
be great.
Rich
8:17 p.m.
Rich,
On Tue, Sep 22, 2015 at 7:25 PM, Rich Felker <dalias(a)libc.org> wrote:
They appear to work, at least for my simple tests.
As far as I can tell, the bFLT format and linker
scripts used have no
way to represent the location/size of the TLS image, so inability to
initialize TLS makes sense. I think this could be solved by having the
linker script put symbols around the TLS image and referencing the
symbols rather than ELF headers to find it. Of course dropping bFLT
and using FDPIC or regular ELF would be the ideal solution.
I've looked at this all recently; see this and the containing thread:
http://lists.nommu.org/pipermail/nommu/2015-September/000037.html
Thanks for the hints, I've only started looking at FDPIC ABI.
So my
questions are:
- are TLS and NPTL supported by uClibc for uclinux?
- if not, what are the supported threading options?
At this point, I think the answer is no, and it would probably be
considerable work to get it working. Nothing that's prohibitively
difficult for someone familiar with the code and linking/binfmt
topics, but still time-consuming.
The old LinuxThreads may or may not work (for some limited definition
of "work") on some NOMMU targets. It probably varies from one to
another so I don't think there's a single answer to your second
question without knowing which target(s) you care about. What I would recommend if you need threads/TLS, but
I'm naturally
biased: I'm presently working on FDPIC-based NOMMU support in musl
libc with thread and TLS support matching normal targets with MMU.
It's already mostly working and progressing rapidly, but the only
supported target so far is SH. Getting more NOMMU targets added would
be great.
I'm currently in the middle of porting musl to xtensa, I guess after
making it work I'll look closer at adding noMMU support to it.
--
Thanks.
-- Max
3132
days inactive
3132
days old
6 comments
3 participants
participants (3)
-
Max Filippov -
Rich Felker -
Sergei Poselenov