[LLVMdev] setrlimit vs ulimt

[Evgeniy Stepanov]

On Thu, May 29, 2014 at 10:44 PM, Greg Fitzgerald <garious at gmail.com> wrote:
>> execv(argv[0]) is a canonical way to restart the
>> process, it's sad that the emulator interferes with that.
>
> We have the option to emulate the instruction set or emulate the OS.
> The former is lighter weight and easy to configure.  The downside is
> that system calls route to the host system.  That can be useful if,
> for example, the executable invokes llvm-symbolizer.
>
> While execv(argv[0]) may be the right way to restart, this process
> doesn't need to be restarted.  It needs to be configured before the
> first invocation.

I must be missing something here. Why does fork-exec for
llvm-symbolizer work, but simple exec(self) does not?
Is it because argv[0] is not what it normally is? Can it be worked around?

>
>
>> Propagating ulimit setting in %run wrapper sounds wrong.
>
> In my opinion, propagating ulimit settings in the wrapper is
> consistent with whitelisting environment variables.

Target platform may be quite different from host and simply
replicating the entire "ulimit -a" would be wrong. Ideally, we need to
propagate only those limits that were set explicitly in the test.
Could we write a ulimit-like utility that would do setrlimit and then
exec the specified binary, like %run %ulimit -s 8192 %t?


>
> -Greg
>
> On Thu, May 29, 2014 at 2:34 AM, Evgeniy Stepanov <eugenis at google.com> wrote:
>> execv(argv[0]) is a canonical way to restart the process, it's sad
>> that the emulator interferes with that.
>>
>> ulimit does not work for me because it needs to run on the device, in
>> the same shell as the test binary.
>> Propagating ulimit setting in %run wrapper sounds wrong.
>>
>>
>> On Wed, May 28, 2014 at 11:43 PM, Greg Fitzgerald <garious at gmail.com> wrote:
>>> Hi Evgeniy,
>>>
>>> This fix causes me trouble in the emulator because of the execv(argv[0]):
>>>
>>> http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20140217/205359.html
>>>
>>> Instead using setrlimit from within the C++ code, can you set the
>>> stack limit using ulimit on the RUN lines?  Also, should this test be
>>> moved to the Posix or Linux directory?
>>>
>>> Thanks,
>>> Greg