Re: [Qemu-devel] [Qemu-ppc] Help needed testing on ppc

[BALATON Zoltan <balaton@eik.bme.hu>]

On Tue, 17 Jun 2014, Tom Musta wrote:
> I am looking at the test case source code and do not see how you are 
> setting the reserved bit.  Maybe I am missing some cleverness in how the 
> test is built?

Probably I should have written it more straight-forward but I wanted it to 
be possible to change it for other tests easily so it's a bit tricky. 
Basically I get the code location by a bl then fetching the link register:

>  asm volatile("mfcr %0               \n\t"
>               "bl 1f                 \n\t"
>               "mfcr %1               \n\t"
>               "mflr 10               \n\t"

and then set the bit with the next three lines after testing the normal 
case:

>               "lwz %0, 36(10)        \n\t"
>               "ori %0, %0, 1         \n\t"
>               "stw %0, 36(10)        \n\t"

Then test again with the bit set:

>               "mfcr %0               \n\t"
>               "bl 1f                 \n\t"
>               "mfcr %2               \n\t"

and exit:

>               "b 2f                  \n\t"
>               "1: stwx %0, %4, %6    \n\t"          <<<<<<<<<<<<< just a normal stwx, right?
>               "blr                   \n\t"
>               "2:                    \n\t"
>                : "=&r"(cr), "=&r"(cr1), "=&r"(cr2), "=m"(val)
>                : "r"(&val), "m"(val), "r"(8)
>                : "r8", "r9", "r10", "cc", "memory");
>
>  prom_printf("old cr  (mem):\t%#x\n", val);
>  prom_printf("old cr  (reg):\t%#x\n", cr);
>  prom_printf("new cr1 (reg):\t%#x\n", cr1);
>  prom_printf("new cr2 (reg):\t%#x\n", cr2);
> }
>
>
> But the objdump of your test binary does not show that it is set either:

It should show in a debugger the second time the stwx is called (it did 
for me).

Regards,
BALATON Zoltan