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Re: Regarding systemtap support for AArch64


On 26 September 2013 20:05, William Cohen <wcohen@redhat.com> wrote:
> On 09/25/2013 11:13 PM, Sandeepa Prabhu wrote:
>> Hi Will, Masami,
>>
>> Nice to hear from you, I am using ARM fast model/Foundation model with
>> ARM v8 upstream kernel and a Linaro minimal busybox based ramdisk,
>> testing with loadable modules for now (so don't have dependency on
>> elfutils or GCC autoconf etc)
>>
>> Would you be interested to use Linaro kprobe work as a base for
>> development and validation of systemtap-aarch64?  We are happy to
>> share a public git repo where 'upstream' kernel can be built with
>> kprobes support, which systemtap team can use for verification.  I can
>> do this soon as I have most things working locally, except for
>> kretprobes and 'boosting' support(systemtap can be run without these I
>> believe).
>>
>> Looking forward for a collaboration :-)
>>
>> Cheers,
>> Sandeepa
>
> Hi Sandeepa,
>
> It is very nice to hear that Linaro has been working on aarch64 kprobes.  Is there a git repository or kernel available that has the aarch64 patches?  Also is there a recommend config file and instructions on how to get a new kernel running on the simulator?
>
> We would like to get systemtap working on aarch64.  There are a number architecture specific things that need to be adjusted in systemtap to support aarch64.  A few of the changes have been pushed into the systemtap git repo, but more are needed in the runtime and some more in the tapset.
>
> Locally I have a ARM fast model/Foundation model set up with Fedora 19.  It can build systemtap from source, but it is pretty slow. Running the systemtap testsuite will probably require access to actual hardware. Otherwise tests will timeout and just fail.

Hi Will,

I would create a linaro git repository and upload all the patches and
config file that are needed to build the kernel with kprobes support,
doing it sometimes early next week and share it on systemtap mailing
list.

As I said, I am using minimal setup (busybox based) and using only
sample kernel modules to verify, have not used sophisticated rootfs
like fedora or ubuntu on the models since any GUI will be run very
slow.  Alternately, do you consider using lightweight command-line
system like LAMP stack (available with linaro public builds) and
cross-compile the systemtap and dependent tools on open-embedded
environment. I understand that minimal system is far away from real
environment where systemtap will be used (like fedora, enterprise
servers) but it should serve as temporary setup until the real
hardware is available.

Thanks,
Sandeepa

>
> -Will
>
>
>>
>> On 26 September 2013 00:15, William Cohen <wcohen@redhat.com> wrote:
>>> On 09/24/2013 04:27 AM, Mark Wielaard wrote:
>>>> On Tue, 2013-09-24 at 08:43 +0530, Sandeepa Prabhu wrote:
>>>>> At Linaro, we are developing support for kprobes (and uprobes) for ARM
>>>>> v8 platform, and interested in running systemtap for validating our
>>>>> work. I wanted to check if the current version of  systemtap support
>>>>> AArch64? Is there a systemtap version I can use to verify kprobes
>>>>> mechanism?
>>>>
>>>> There is a fedora bug tracking support work items:
>>>> https://bugzilla.redhat.com/show_bug.cgi?id=926602
>>>> For elfutils you might want to try the pmachata/aarch64 in upstream git.
>>>> https://git.fedorahosted.org/cgit/elfutils.git/log/?h=pmachata/aarch64
>>>> It isn't fully ready yet, but I am sure Petr would like some extra
>>>> testing help.
>>>>
>>>> Cheers,
>>>>
>>>> Mark
>>>>
>>>
>>> Hi,
>>>
>>> My aarch64 simulator is running an old 3.9+ kernel and I don't have all the other kernel-devel related stuff to instrument that kernel. As a work around I have been using a 3.12-rc0 rpm.  Also trying to avoid needing the elfutils at the moment, so I am running some thing like the following command to see what breaks for a really simple "hello world" script:
>>>
>>> sudo ../install/bin/stap  -v -m hello -r 3.12.0-0.rc0.git20.1.x1.fc19.aarch64 -p4 -k -e 'probe begin {printf("hello world\n")}'
>>>
>>> The software simulator is really slow and it looks like the testsuite is probably going to time out for the tests.
>>>
>>> -Will
>


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