Re: [Qemu-devel] [Question]Support of China loogson processor

[Paolo Bonzini <pbonzini@redhat.com>]

On 16/04/2015 21:25, Leon Alrae wrote:
> On 16/04/15 16:17, Paolo Bonzini wrote:
>>
>>
>> On 16/04/2015 17:05, Leon Alrae wrote:
>>> On 16/04/2015 13:02, Paolo Bonzini wrote:
>>>>
>>>>
>>>> On 16/04/2015 13:07, Leon Alrae wrote:
>>>>> Since I also haven't had a chance to test Loongson emulation, I thought
>>>>> I'd give it a try (TCG only, Loongson-2E cpu and fulong2e machine).
>>>>>
>>>>> Good news is that I'm able to get to the login prompt using ancient QEMU
>>>>> v1.0, kernel 2.6.33 (with additional patch from
>>>>> https://lists.gnu.org/archive/html/qemu-devel/2010-06/msg02566.html) and
>>>>> some old debian image I had handy. However, in any newer version
>>>>> starting from v1.1.0 of QEMU something goes horribly wrong and it just
>>>>> segfaults somewhere inside hw/bonito.c quite early during kernel
>>>>> booting.
>>>>
>>>> Where exactly?  If it's related to the memory API conversion, it may be
>>>> easy to fix.  I can look at a backtrace (or you can just put the Debian
>>>> image somewhere I can grab it).
>>>
>>> Bisect points at: 5312bd8b3152f8d4fcf9389ba54e32b09f4b4093
>>>
>>> Crash occurs during the first access, below there is backtrace from
>>> working and not working case:
>>
>> This is my best guess...
>>
>> diff --git a/hw/pci-host/bonito.c b/hw/pci-host/bonito.c
>> index 8bdd569..8134d0b 100644
>> --- a/hw/pci-host/bonito.c
>> +++ b/hw/pci-host/bonito.c
>> @@ -233,7 +233,7 @@ static void bonito_writel(void *opaque, hwaddr addr,
>>      uint32_t saddr;
>>      int reset = 0;
>>  
>> -    saddr = (addr - BONITO_REGBASE) >> 2;
>> +    saddr = addr >> 2;
>>  
>>      DPRINTF("bonito_writel "TARGET_FMT_plx" val %x saddr %x\n", addr, val, saddr);
>>      switch (saddr) {
>> @@ -295,7 +295,7 @@ static uint64_t bonito_readl(void *opaque, hwaddr addr,
>>      PCIBonitoState *s = opaque;
>>      uint32_t saddr;
>>  
>> -    saddr = (addr - BONITO_REGBASE) >> 2;
>> +    saddr = addr >> 2;
>>  
>>      DPRINTF("bonito_readl "TARGET_FMT_plx"\n", addr);
>>      switch (saddr) {
>>
> 
> Nice. Thanks!
> 
> Would you send the patch or should I do this? With this fix fulong2e
> machine is brought back to life. It would be great to have it in 2.3.

You can send a pull request directly (add my Signed-off-by and Cc:
qemu-stable@nongnu.org, please), but it is possible Peter will tell you
to wait for 2.3.1.  It's been broken for a few years already. :)

Paolo