Fwd: Launching C userland code with rumprun

  • From: David CARLIER <devnexen@xxxxxxxxx>
  • To: rumpkernel-users@xxxxxxxxxxxxx, pooka@xxxxxx
  • Date: Sun, 21 Jun 2015 14:08:19 +0100

On 21 June 2015 at 13:40, Antti Kantee <pooka@xxxxxx> wrote:

On 21/06/15 12:12, David CARLIER wrote:

Hi and thanks in advance for the help.

I compiled a C code of my own with static version of PCRE library, then
"baked" it. This C code needs a file input which i put inside an ISO.

Then I used rumprun and had still trouble with qemu, had bunch of
pagefault
error issued. It is solved now but I have still trouble to launch via
Linux/xen like this

rumprun xen -d -i -b jsons.iso,/jsons -- app.bin.xen /jsons/sample.json

Then I get an infinite page caller <address> ... displayed and after some
minutes that hang, very hard to shut it down or even getting out of the
console (Sorry in advance I never used Xen before so I m pretty ignorant).


You say it's C code of your own. Are you confident that it's correct? Did
you try running it as a normal userspace binary under valgrind? I often
find the most bugs in my own code ... ;)


Yes tested under lot of different oses, primarily Linux/valgrind but also
OpenBSD/MALLOC_STATS, FreeBSD/jemalloc etc etc there is no corrupted
pointer or nasty double free somewhere :-) Anyway that work very fine under
qemu I guess I did something wrong in the compilation chain for xen case (I
have compiled two different versions of PCRE one for qemu usage one for xen
then the library of this C code and in the end the executable, all
stoically compiled for each version). In fact I just try to understand how
all work before doing more complex use cases :-)



Can you copypaste the exact error message?


The error I get is infinite lines like this and that never stop

base is 0xccf848 caller is 0x109ab
base is 0xccf8f8 caller is 0x109ab

and so on ...




Generally, I find debugging with the xen platform harder than debugging
with hw because gdbsx seems very temperamental. If you can repeat the
errors under qemu, it's easy to track them down. (nb. rumprun kvm is
horrible for debugging with gdb, but rumprun qemu works perfectly)


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