Here is another try, there are now separate libs for printf, putchar and assert plus some new simple apps. The app myassert shows overriding of the assert methods, here is the commit message:

    libsel4 without dependencies on libc.

    

    There are now separate libs for benchmark, assert, printf and putchar:

    

      libs/libsel4_benchmark

      libs/libsel4_assert

      libs/libsel4_printf

      libs/libsel4_putchar

    

    And some simple test apps:

    

      apps/test-newlibs -> test simple things

      apps/min-app -> Does nothing, just retuns 0

      apps/hw -> tests putchar

      apps/helloworld -> tests printf

      apps/assert -> tests seL4_Asserts ..

      apps/myassert -> tests that we can override _seL4_AssertFail ..

      apps/bootinfo -> tests that we can access seL4_BootInfo

    

    The primary changes are introducing sel4_types.h and removing std* types

    plus porting assert and IO code from the kernel to libsel4_assert

    and libsel4_printf, libsel4_putchar.

    

    This means the code within libraries do not overload any typical libc

    entities. Instead the libraries use types like seL4_Uint32 ... instead of

    uint32_t. And printf is now seL4_Printf and assert is seL4_Assert ....

    

    Finally, the only file modified that effects kernel code is

    kernel/tools/bitfield_gen.py. It needed to be modified as it generates

    files for both kernel and user space. And for user space the generated code

    (types_gen.h) needed to use the new types and asserts. The changes should

    not change what is generated for the kernel and I did a comparison of

    kernel_final.{c|s} before and after my change and the only differences

    were time stamps.

On Thu, Jul 2, 2015 at 9:47 PM Adrian Danis <Adrian.Danis@nicta.com.au> wrote:

My main problem with this change remains bringing in all of this IO implementation into the C library. As far as I can tell all of the putchar, printf, varargs, halt etc is introduced just to support assertions. Why not rely on the user system to provide the actual assertion implementation, allowing all of the I/O code to be moved out of this library?

i.e. define assert to something like

#ifdef NDEBUG
#define libsel4_assert(x) (void)0
#else
#define libsel4_assert(x) ((void)((x) || (__assert_fail(#x, __FILE__, __LINE__, __func__),0)))
#endif
void __assert_fail (const char *, const char *, int, const char *);

And then rely on the user code to provide an implementation of __assert_fail, which if they are linking against the muslc library is already provided.

Adrian

On 03/07/15 13:11, Wink Saville wrote:

@Harry,

I'll fix the comment.

Using print_string is a good idea, I'll look into how to create a string with __FILE__, __LINE__, __func__ at compile time rather than runtime, maybe just using paste ("#") will work.

I guess my feeling is asserts should work without the user having to do extra steps, so there should be a default one in any case. Also, I believe it can be overridden at link time by the user supplying their own implementation.

On using "assert 0" to eliminate duplicate code, do you mean eliminate "_seL4_Fail" and just have "_seL4_AssertFail"?

On Thu, Jul 2, 2015 at 7:52 PM Wink Saville <wink@saville.com> wrote:

Moving sel4_benchmark.h into libsel4 was something I was thinking we might do. I'm thinking longer maybe it could significantly expand and possibly have supporting c sources so that's why I kept it separate for now.

On using error rather than message, NP, I chose message because I didn't want to always force people to change the configuration, but maybe that would be error is better.

Some what related, I've chosen to always assume putchar would be available in some configurations, so I created sel4_debug_printf.h/sel4_debug_assert.h which uses NDEBUG to conditionally turn off/on asserts and printf. Where as sel4_printf.h/sel4_assert.h assumes putchar would always be available. So this a different behavior then previously and people may not like it.

As I said, still quite a bit to discuss and of course, the main one: is having libsel4 independent of libc something that's desirable? Which, obviously you don't think it is, but others seem to like it, so we'll see what happens.

-- Wink

On Thu, Jul 2, 2015, 5:25 PM Matthew Fernandez <matthew.fernandez@nicta.com.au> wrote:

Though I'm still opposed to this change overall, my two cents on the current state:

  - Should we just put the benchmarking code in libsel4bench [0]? I realise the former is for
benchmarking the kernel and the latter is (arguably) for benchmarking userspace, but it seems to me
a better home for it.

  - You've used `#pragma message` in one instance. I would prefer `#error` for consistency, though
I'm aware `#pragma message` is more portable. Moreover, why are we emitting messages here in the
first place? It's a perfectly valid (in fact the default) configuration to have the benchmarking
syscalls disabled.

[0]: https://github.com/seL4/libsel4bench

On 03/07/15 10:19, Wink Saville wrote:
> One other note, this isn't done. It still needs to be integrated with muslc (libc) and at a minimum
> seL4_Halt needs to be properly implemented. And I'm sure there will be plenty of other changes
> needed but I hope we're closer.
>
> On Thu, Jul 2, 2015 at 5:11 PM Wink Saville <wink@saville.com <mailto:wink@saville.com>> wrote:
>
>     Here <https://github.com/winksaville/sel4-min-sel4/tree/no-libc3> is try #3, I've pasted the
>     commit message below as it tells the story, let me know what you think:
>
>          libsel4 with no libc dependency.
>          The primary changes are introducing sel4_types.h and removing std* types
>          plus porting assert and printf code from the kernel to libsel4. All of
>          this means the code within libsel4 does not overload any typical libc
>          entities. So now libsel4 uses types like seL4_Uint32 ... instead of
>          uint32_t. And printf is now seL4_Printf and assert is seL4_Assert ....
>          I'm also using sel4_ prefixes for various files as I felt it was more
>          consistent with the names of the entities within the files.
>          The only new library is libsel4_benchmark and since it consists of just
>          sel4_benchmark.h we might want to move that back into libsel4. I would
>          have liked to move out libsel4_assert, libsel4_printf and libsel4_putchar
>          but since asserts are used by low level generated code I couldn't come up
>          with a good way of doing that.
>          Finally, the only file modified that effects kernel code is
>          kernel/tools/bitfield_gen.py. It needed to be modified as it generates
>          files for both kernel and user space. And for user space the generated code
>          (types_gen.h) needed to use the new types and asserts. The changes should
>          not change what is generated for the kernel and I did a comparison of
>          kernel_final.{c|s} before and after my change and the only differences
>          were time stamps
>
>     -- Wink
>
>     On Mon, Jun 29, 2015 at 7:07 PM Wink Saville <wink@saville.com <mailto:wink@saville.com>> wrote:
>
>         Will do.
>
>
>         On Mon, Jun 29, 2015, 7:05 PM Anna Lyons <Anna.Lyons@nicta.com.au
>         <mailto:Anna.Lyons@nicta.com.au>> wrote:
>
>
>             Hi,
>
>              >
>              > Currently there is at least one known problem, I modified
>              > bitfield_gen.py so types_gen.h has no asserts since at the moment the
>              > kernel uses assert and userspace is libsel4_assert. We could either do
>              > something like I've done and remove them or change the kernel to use
>              > libsel4_assert or something else.
>              >
>
>             The asserts are really important to avoid horrible bugs when using
>             functions created by the bitfield generator, so if we go ahead with this
>             let's make sure they survive in some form.
>
>             Cheers,
>             Anna.
>
>             ________________________________
>
>             The information in this e-mail may be confidential and subject to legal professional
>             privilege and/or copyright. National ICT Australia Limited accepts no liability for any
>             damage caused by this email or its attachments.
>
>             _______________________________________________
>             Devel mailing list
>             Devel@sel4.systems
>             https://sel4.systems/lists/listinfo/devel
>
>
>
> _______________________________________________
> Devel mailing list
> Devel@sel4.systems
> https://sel4.systems/lists/listinfo/devel
>

________________________________

The information in this e-mail may be confidential and subject to legal professional privilege and/or copyright. National ICT Australia Limited accepts no liability for any damage caused by this email or its attachments.

_______________________________________________
Devel mailing list
Devel@sel4.systems
https://sel4.systems/lists/listinfo/devel