I mean, there is only ONE thread in UML that intercepts The system calls and services them. Can we have more such threads in the kernel ?
-----Original Message----- From: Nalli, Sanketh Sent: Monday, June 02, 2014 6:29 PM To: user-mode-linux-user@lists.sourceforge.net; 'Richard Weinberger' Cc: Volos, Haris Subject: RE: [uml-user] invalid /proc/PID/exe in UML processes Okay, so I've found a way around the invalid exe symlink. I don't need that anymore. The next challenge is concurrency in UML. I wrote a simple program that launches 10 pthreads, Each of which makes some system calls in an infinite loop. I notice that even though there are 10 threads in my dummy program, There is only ONE UML kernel thread. Is this correct ? If so, does this mean that UML kernel is serializing the execution ? Is there some way of making UML kernel multi-threaded ? -----Original Message----- From: Richard Weinberger [mailto:rich...@nod.at] Sent: Monday, June 02, 2014 1:46 PM To: Nalli, Sanketh Cc: user-mode-linux-user@lists.sourceforge.net Subject: Re: [uml-user] invalid /proc/PID/exe in UML processes Am 02.06.2014 22:42, schrieb Nalli, Sanketh: > Nope, but here is some bootlog Hmm, I have no idea so far. Applications running under valgrind or other debuggers suffered from the issue that /proc/pid/exe is empty. > The host does not have skas3 patch > Do you think that is the problem ? Nope. SKAS0 works fine. > Which host shd I use that already has this patch (I mean I cud patch > the host myself but if there is one Already present, that is good !) > > Core dump limits : > soft - 0 > hard - NONE > Checking that ptrace can change system call numbers...OK Checking > syscall emulation patch for ptrace...OK Checking advanced syscall > emulation patch for ptrace...OK Checking for tmpfs mount on > /dev/shm...nothing mounted on /dev/shm Checking PROT_EXEC mmap in > /tmp/...OK Checking for new_mm and switch_mm support in the host: > /proc/self/mm ... Failed - > No such file or directory > Checking for the skas3 patch in the host: > - /proc/mm...not found: No such file or directory > - PTRACE_FAULTINFO...not found > - PTRACE_LDT...not found > UML running in SKAS0 mode > Adding 20606976 bytes to physical memory to account for exec-shield > gap Linux version 2.6.24-g91525300-dirty > (jd...@amd64.user-mode-linux.org) (gcc version 4.1.1 20070105 (Red Hat > 4.1.1-51)) #1 Mon Jan 28 12:03:41 EST 2008 Wow. This UML is horrible old. Thanks, //richard ------------------------------------------------------------------------------ Learn Graph Databases - Download FREE O'Reilly Book "Graph Databases" is the definitive new guide to graph databases and their applications. Written by three acclaimed leaders in the field, this first edition is now available. Download your free book today! http://p.sf.net/sfu/NeoTech _______________________________________________ User-mode-linux-user mailing list User-mode-linux-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user
