Re: [Qemu-devel] SPARC not booting SMP Linux kernel

[Artyom Tarasenko <atar4qemu@googlemail.com>]

2010/6/22 陈宇飞 <cyfdecyf@gmail.com>:
>
> On 2010-6-22, at 下午1:46, Artyom Tarasenko wrote:
>
>> 2010/4/28 陈宇飞 <cyfdecyf@gmail.com>:
>>> I've tested the latest git HEAD version. But still has the problem.
>>>
>>> Investigating Linux kernel execution shows that the function which will clear the  interrupt is not executed.
>>>
>>> Here's the relevant kernel code.
>>>
>>> maybe_smp4m_msg:
>>>       GET_PROCESSOR4M_ID(o3)
>>>       set     sun4m_interrupts, %l5
>>>       ld      [%l5], %o5
>>>       sethi   %hi(0x40000000), %o2
>>>       sll     %o3, 12, %o3
>>>       ld      [%o5 + %o3], %o1
>>>       andcc   %o1, %o2, %g0
>>>       be,a    smp4m_ticker     /* Jump to smp4m_ticker, which will clear interrupt */
>>>        cmp    %l7, 14          /* Comparing the interrupt level*/
>>>       st      %o2, [%o5 + 0x4]
>>>       WRITE_PAUSE
>>>       ld      [%o5], %g0
>>>       WRITE_PAUSE
>>>       or      %l0, PSR_PIL, %l4
>>>       wr      %l4, 0x0, %psr
>>>       WRITE_PAUSE
>>>       wr      %l4, PSR_ET, %psr
>>>       WRITE_PAUSE
>>>       call    smp_reschedule_irq
>>>        nop
>>>
>>>       RESTORE_ALL
>>>
>>
>> actually what would be interesting to look at is the code of
>> smp4m_ticker - the routine which should clear the irq.
>>
>>>> On 4/27/10, 陈宇飞 <cyfdecyf@gmail.com> wrote:
>>>>> Actually this has been test before.
>>>>>
>>>>> http://lists.gnu.org/archive/html/qemu-devel/2006-08/msg00512.html
>>>>
>>>> That was before I added SMP support to OpenBIOS.
>>>>
>>>>> I've tested Debian 3.1 (with Linux 2.4.27.3) and Debian 4.0 (with
>>>>> Linux 2.6.18.6), on both qemu 0.10.6 and 0.12.3, emulating machine is
>>>>> set to SS-20.
>>>>>
>>>>> 1. non-smp kernel successfully boots with both -smp 1 or -smp 2.
>>>>> 2. smp kernel can only boot with -smp 1. (The 2.6 kernel is cross
>>>>> compiled by gcc 4.2.4 since no binary package is available)
>>>>>
>>>>> Some investigation with qemu's debug message and Linux kernel dump
>>>>> (the 2.6 kernel) shows that
>>>>>
>>>>> 1. When the boot cpu tries to start cpu 1, cpu 1 calls
>>>>> local_irq_enable. After that, cpu 1 get's lot's of level 14 interrupt.
>>
>> Is 'cpu 1' the first or the second cpu?
>
> 'cpu 1' is the second cpu.
>
>>
>>>>> 2. Printing out the executed TBs' pc values shows that kernel
>>>>> interrupt handler is executed.
>>>>> 3. Qemu's do_interrupt debug message shows that cpu 1 always get level
>>>>> 14 interrupt at the same pc, which is the nop instruction just after
>>>>> the "mov %g1, %psr" instruction.
>>>>>
>>>>> I guess that the interrupt is not cleared even after the execution of
>>>>> the interrupt handler. I've found debian installation report which
>>>>> boots smp linux kernel, so I thinks this problem is caused by qemu?
>>
>> Can you please try the patch http://patchwork.ozlabs.org/patch/56338/ ?
>> Does it improve the situation?
>
> I've tested this patch, but still have the same problem.

Can you try enabling debug in hw/slavio_timer.c and hw/slavio_intctl.c
and look whether the second cpu tries to write any register there
between the interrupts?


>>>>> I'm tring to fix this problem but I'm not familiar with sparc
>>>>> architecture, is there any clue?
>>>>
>>>> This sounds awfully familiar to the problems Solaris had with
>>>> interrupts. Does the problem still exist with git HEAD version of
>>>> QEMU?

> --
> Best regards,
> Chen Yufei
>
>

-- 
Regards,
Artyom Tarasenko

solaris/sparc under qemu blog: http://tyom.blogspot.com/