Re: [Adeos-main] [Vortx86DX] What's wrong with kernels upper than 2.6.30.10 ?

[Jan Kiszka <jan.kiszka@domain.hid>]

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Jan Kiszka wrote:
> Gilles DOFFE wrote:
>> Hello,
>>
>> I try to install a real-time Linux kernel on a Roboard based on a Vortex86DX
>> (a x486 with TSC).
>>
>> All works fine with :
>> Linux Kernel 2.6.30.10
>> Xenomai 2.5.1
>> Adeos patch adeos-ipipe-2.6.30.8-x86-2.4-09.patch
>>
>> But, for all kernels upper or equal to 2.6.31, I always get a double fault
>> when testing WP bit. I have this double fault just after that :
>>
>> *Checking if this processor honours the WP bit even in supervisor mode...*
>>
>> I traced with some simple printk that the problem occurs in this function,
>> at the end or after the call of fix_to_virt  :
>>
>> *static noinline int do_test_wp_bit(void)
>> {
>>         char tmp_reg;
>>         int flag;
>>
>>         __asm__ __volatile__(
>>                 "       movb %0, %1     \n"
>>                 "1:     movb %1, %0     \n"
>>                 "       xorl %2, %2     \n"
>>                 "2:                     \n"
>>                 _ASM_EXTABLE(1b,2b)
>>                 :"=m" (*(char *)fix_to_virt(FIX_WP_TEST)),
>>                  "=q" (tmp_reg),
>>                  "=r" (flag)
>>                 :"2" (1)
>>                 :"memory");
>>
>>         return flag;
>> }*
>>
>> I'm (quasi) sure that the problem is not that function, due to it works when
>> the kernel is not patched.
>> But where should I search ?
>>
>> Can you give me some indications ?
> 
> Does applying this patch [1] happen to change the picture?

To answer myself: As the Vortex is 32-bit, this patch cannot make a
difference.

> 
> If not, please provide your .config.

So this is now important. Probably reproducible in a VM, thus also
easily debuggable.

Jan


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