RE: [microblaze-uclinux] PPPD problem with fork()

["Bartsch Carsten" <cbartsch@xxxxxxxxxx>]

Attached you will find the test. 
Make it with the default Makefile generated by petalinux-new-app.
Btw: I'm using a petalinux-mmu-v0.10 on a Sp3A-DSP-1800A-Starter.
It was only tested on my platform, not on a reference platform.

This following text is the output after a normal make:

# /ua/process-test/process-test
the main program process ID is 104
before forking: textptr=bf907e00 &textptr=bf907df8 *textptr=I am a
stupid text.
before forking: numpointer=bf907df4 &numptr=bf907dfc *numptr=9876
before forking: number=9876 &number=bf907df4

this is the parent process, with id 104  the child's process ID is 105
parent        : textptr=bf907e00 &textptr=bf907df8 *textptr=I am a
stupid text.
parent        : numptr=bf907df4 &numptr=bf907dfc *numptr=9876
parent        : number=9876 &number=bf907df4

this is the child process, with id 105
child         : textptr=bf907e00 &textptr=2 *textptr=I am a stupid text.
child         : numptr=bf907df4 &numptr=0 *numptr=9876
child         : number=9876 &number=0


The following text is the output after removing the -Os option:

# /ua/process-test/process-test
the main program process ID is 106
before forking: textptr=bfa67e04 &textptr=bfa67e1c *textptr=I am a
stupid text.
before forking: zahlpointer=bfa67e18 &numptr=bfa67e20 *numptr=9876
before forking: number=9876 &number=bfa67e18

this is the parent process, with id 106  the child's process ID is 107
parent        : textptr=bfa67e04 &textptr=bfa67e1c *textptr=I am a
stupid text.
parent        : numptr=bfa67e18 &numptr=bfa67e20 *numptr=9876
parent        : number=9876 &number=bfa67e18

this is the child process, with id 107
child         : textptr=bfa67e04 &textptr=bfa67e1c *textptr=I am a
stupid text.
child         : numptr=bfa67e18 &numptr=bfa67e20 *numptr=9876
child         : number=9876 &number=bfa67e18


The difference is the addresses. In the child process the content is
there but the addresses are lost.



-----Mensaje original-----
De: owner-microblaze-uclinux@xxxxxxxxxxxxxx
[mailto:owner-microblaze-uclinux@xxxxxxxxxxxxxx] En nombre de John
Williams
Enviado el: jueves, 12 de marzo de 2009 12:06
Para: microblaze-uclinux@xxxxxxxxxxxxxx
Asunto: Re: [microblaze-uclinux] PPPD problem with fork()

Hi Carsten,

On Wed, Mar 4, 2009 at 1:07 AM, Bartsch Carsten <cbartsch@xxxxxxxxxx>
wrote:
> with a small test-application I see the same problem (using MMU and
fork()).
>
> My first impression is that this happens if you want to share only a
> pointer. You could try sharing other "padding"- variables (use them in
the
> child). Some addresses look strange in the childs process. I didn't
dig
> deeper yet.

Can you please post this test app?  The smaller the better :)

Thanks,

John
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Attachment: process-test.c
Description: process-test.c