[bug #15] usblib timeouts does not work correctly on solaris platforms

[avrs-admin]

mcerveny 2012-02-27 22:00:54

Hello.

There is problem with usb_bulk_read/usb_bulk_write timeouts in usblib( 0.1.8) on opensolaris/solaris platforms (probably on all <1.0 usblib versions). I reprogrammed jtag2usb.cc to use thread model (instead of multiprocess) for read and write threads and use blocking calls (timeout = 0).

M.C>

avarice-2.12-30-usbthread.patch svn297.diff

This issue was migrated from https://sourceforge.net/p/avarice/bugs/15/

[avrs-admin]

mcerveny 2012-02-27 22:00:55

multithread with blocking calls on usb

[avrs-admin]

joerg_wunsch 2012-02-27 22:22:55

Sorry, the source tree heavily changed lately, since I rewrote the entire error handling to use C++ exceptions rather than the crocky mix between return codes, trying to call exit(), or just ignoring the error that used to be there before.

Consequently, your patch no longer applies. :-( Could you rewrite it against the SVN version? If I tried adapting your patch, there's a high risk I might break something, and I don't have a Solaris machine around wich is equipped with USB to really test it.

Also, I'm not sure I'd like to have the threads version as a general version, at least not until it's proven it will work well on all the existing platforms (including Cygwin!). Thus, I'd prefer it the threads code were #ifdef'ed, with either a manual or an automatic detection (by probing for Solaris) in the configure.ac script.

Finally, it seems on Solaris, no further flags to the compiler/linker are needed to tell them to build a threaded executable. Other systems do require additional options here (like -pthread on the entire toolchain, or just -lpthread on the linker commandline), so we have to add autoconf magic for that.

Given the amount of work required for all that, isn't it perhaps better to implement an alternative, libusb-1 based version? As libusb-1 uses a pollable descriptor (I've heard so, I hope it really does), there's no longer a need for the multiprocessing or multithreading approach at all. That approach has only been introduced to be able to poll on both, the ICE connection over USB as well as the GDB socket descriptor at the same time, which libusb-0.1 doesn't allow for. (Again, the libusb-1 based implementation should be #ifdef'ed, so platforms not offering a port of libusb-1 could continue to use the existing approach.)

[avrs-admin]

mcerveny 2012-02-27 23:21:32

svn diff to 297

[avrs-admin]

mcerveny 2012-02-28 00:09:05

Also, I'm not sure I'd like to have the threads version as a general version, at least not until it's proven it will work well on all the existing platforms (including Cygwin!). Thus, I'd prefer it the threads code were #ifdef'ed, with either a manual or an automatic detection (by probing for Solaris) in the configure.ac script.

Threads is first step, communication rewrite should be nice (replace pipe with some condvars...) :-).

Finally, it seems on Solaris, no further flags to the compiler/linker are needed to tell them to build a threaded executable. Other systems do require additional options here (like -pthread on the entire toolchain, or just -lpthread on the linker commandline), so we have to add autoconf magic for that.

man page says "cc -mt -lpthread ..." but works without it (maybe some gcc/libgcc magic).

Given the amount of work required for all that, isn't it perhaps better to implement an alternative, libusb-1 based version? As libusb-1 uses a pollable descriptor (I've heard so, I hope it really does)

There is the "Oracle" problem. Oracle closed OpenSolaris and ignoring to use *Solaris on workstation (eg, usb rich device), The usblib will not be updated to 1.x :-( (actual version is 0.1.8). There are other derived distributions (Illumos/OpenIndiana) that may update the usblib. The Solaris usblib is wrapper to Solaris usba/ugen architecture that may be unwrapable to usblib>1.0.

I do not say that patch must be integrated. I have sometimes problem with communication with avr-gdb/jtagice. I suppose that is due to desynchronization between reader-writer threads :-(

M.C>

[avrs-admin]

joerg_wunsch 2012-11-02 22:38:43

After the next release, I'm all open if someone wants to rewrite the USB stuff.

In theory, with the libusb 1.0 API, I think we don't need either threads or multiprocessing (or condvars) at all. The current "USB daemon" approach has only been implemented in order to be able to poll() (or select(), doesn't matter) for both, USB as well as GDB communication in the master process. However, since the libusb 0.1 API doesn't provide a normal Unix filedescriptor, the "USB daemon" served as a helper process for libusb, providing a pollable pipe descriptor to the master process.

Anyway, I don't want to lose Cygwin portability with all this. That's probably the only part that has to be verified before switching to something completely different.

[avrs-admin]

joerg_wunsch 2012-12-04 15:59:50

I somewhat got your point about not being able to use the libusb-1 API for Opensolaris (though, well, it's always a matter of someone just doing it -- there's an opensource libusb where Opensolaris could add their own support, independent of what has been inherited from Sun).

Anyway, as I don't trust the threading to experience less problems for other (non-Opensolaris) users, I'd like to have this as a configuration option, so the actual implementation is #ifdef'ed appropriately. That way, people could decide at compile-time whether they'd like to use the thread model or multiprocess model. As the patch needs some additional work due to the recent error handling changes, please change it that way. I don't care much whether you also add the configuration file handling (--enable-threads or such) or not, I could easily do that myself. For testing, you can just edit the generated Makefile to add the respective -DENABLE_THREADS option manually.

[avrs-admin]

joerg_wunsch 2012-12-19 14:10:45.962000

I changed it a little to adopt my recent changes (use the USB zero-length/full-length packet mechanism to decide about when a message is complete, rather than pre-parsing the JTAGICEmkII data frames), but otherwise, committed it now. From what I can tell so far, it appears to work well, but please check the SVN version yourself.

I also had to add some autoconf magic to detect the compiler and library options that are needed for pthreads.

I did not test the Windows build yet under Cygwin, but Cygwin claims to be pthreads compliant, so I hope it'll do fine there.

[avrs-admin]

joerg_wunsch 2012-12-19 20:32:39.815000

Ah, cr*p. The current code completely breaks on FreeBSD. :-( It just passes a single message along the socket pair, and then jams.