Re: [Valgrind-developers] Porting Queries

[Subhashish P. <sp...@gm...>]

Hello again!

I have some new questions that I'd like to understand about
unimplemented system calls.

The eject.c example provided here at http://leapster.org/linux/cdrom/
will compile successfuly
with a #include <stdlib.h>. Then when run it under as "valgrind
./eject', it still reports:

==6212== Command: ./eject
==6212==
==6212== Warning: noted but unhandled ioctl 0x5309 with no size/direction hints
==6212==    This could cause spurious value errors to appear.
==6212==    See README_MISSING_SYSCALL_OR_IOCTL for guidance on
writing a proper wrapper.

Why would that be? (since ioctls are wrapped in
coregrind/m_syswrap/syswrap-linux.c)

What is this "ioctl 0x5309 with no size/redirection hints" and how
could that be solved
by PRE or POST functions?

Or specifically, I couldn't understand the 0x5309 operation code
context as explained in this post on this mailing list below:
<http://valgrind.10908.n7.nabble.com/noted-but-unhandled-ioctl-0xae03-with-no-size-direction-hints-tp38957p38959.html>

How can we use that opcode to write wrappers?


On Sat, Jan 25, 2014 at 7:04 PM, Subhashish Pradhan <sp...@gm...> wrote:
> Thanks!
>
> Regards,
> Subhashish
>
>
> On Sat, Jan 25, 2014 at 5:23 PM, Philippe Waroquiers
> <phi...@sk...> wrote:
>>
>> On Sat, 2014-01-25 at 09:37 +0530, Subhashish Pradhan wrote:
>> > Hello again,
>> >
>> >
>> > My target os is GNU Hurd.
>> >
>> >
>> > Basically I'd have to implement the system call wrappers in coregrind
>> > or is there something else required?
>> For sure, there will be a lot of other things (e.g. the configure
>> machinery, the tests, assembly code, ...) but the source of information
>> is the sources :).
>>
>> In the c code, basically, everywhere where you will find a bunch of
>>   #if defined ..
>>   #elif defined ...
>> which are mentioning linux/darwin, you will very probably have
>> to do something for VGO_hurd and/or VGP_x86_hurd and/or VGP_amd64_hurd
>> (or any other cpu you want to support for hurd).
>>
>>
>> >
>> >
>> > I would look into  and compare with the Solaris port - seems nicely
>> > documented.
>> >
>> >
>> > Also, I would like to discuss about how they are implemented. There
>> > are the PRE(sys_call) and POST(sys_call), the system call table (at
>> > the end, that I seem to get) and some other functions. What are these
>> > other functions that we see in the coregrind/m_syswrap/syswrap-os.c?
>> >
>> > So how does this composition of functions work as a prt of
>> > syswrap-os.c ?
>> Porting to a new os is a non trivial work, I guess you will have
>> to first do a lot of initial reading/work/experimenting/...
>> before specific problems/questions might be discussed.
>>
>> Sorry for not be able to help more
>>
>> Philippe
>>
>>
>>
>