Re: [Qemu-devel] [PATCH] pc: Don't listen on debug ports by default

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2012-09-11 14:14, Julien Grall wrote:
> On 09/11/2012 12:57 PM, Jan Kiszka wrote:
> 
>> On 2012-09-11 13:48, Jan Kiszka wrote:
>>> On 2012-09-11 13:27, Julien Grall wrote:
>>>> On 09/11/2012 10:25 AM, Avi Kivity wrote:
>>>>> On 09/11/2012 12:15 PM, Avi Kivity wrote:
>>>>>    
>>>>>> On 09/04/2012 06:13 PM, Julien Grall wrote:
>>>>>>      
>>>>>>> This is the nineth version of patch series about ioport registration.
>>>>>>>
>>>>>>> Some part of QEMU still use register_ioport* functions to register ioport.
>>>>>>> These functions doesn't allow to use Memory Listener on it.
>>>>>>>        
>>>>>> Thanks, applied all (w/ updated patch 4), will push shortly.
>>>>>>
>>>>>>
>>>>>>      
>>>>> Aborts with the command line
>>>>>
>>>>>    qemu-system-x86_64 -device isa-debugcon,iobase=0x402,chardev=stdio -chardev stdio,id=stdio
>>>>>
>>>>>
>>>>>    
>>>>
>>>> I have bisected and found the problem with bochs_bios_init in hw/pc.c.
>>>> Bosch already register the iport 0x402. I'm not sure that it's a bug.
>>>> In fact register_ioport_read/write check if the current ioport is used
>>>> with the opaque variable.
>>>> Before my patch, bochs_bios_init registered it's ioport with opaque
>>>> NULL, so if someone (like debugcon) wants to use the ioport there is
>>>> no problem. But now, I used portio_list_init to register bochs ioport,
>>>> so the opaque is not NULL.
>>>> I don't really know how to resolve this problem. Perhaps we could
>>>> just improve the debug message.
>>>
>>> My suggestion:
>>>
>>> pc: Don't listen on debug ports by default
>>>
>>> Only listen on debug ports when we also handle them. They are better
>>> handled by debugcon these days which is runtime configurable.
>>>
>>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>>>
>>> diff --git a/hw/pc.c b/hw/pc.c
>>> index 112739a..70abf0e 100644
>>> --- a/hw/pc.c
>>> +++ b/hw/pc.c
>>> @@ -539,9 +539,9 @@ static void bochs_bios_write(void *opaque, uint32_t addr, uint32_t val)
>>>      case 0x401:
>>>          /* used to be panic, now unused */
>>>          break;
>>> +#ifdef DEBUG_BIOS
>>>      case 0x402:
>>>      case 0x403:
>>> -#ifdef DEBUG_BIOS
>>>          fprintf(stderr, "%c", val);
>>>  #endif
>>>          break;
>>>
>>
>> OK, ket's try properly again:
>>
>> ----8<-----
>>
>> Only listen on debug ports when we also handle them. They are better
>> handled by debugcon these days which is runtime configurable.
>>
>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>> ---
>>  hw/pc.c |    6 ++++--
>>  1 files changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/hw/pc.c b/hw/pc.c
>> index 112739a..134d5f7 100644
>> --- a/hw/pc.c
>> +++ b/hw/pc.c
>> @@ -539,12 +539,12 @@ static void bochs_bios_write(void *opaque, uint32_t addr, uint32_t val)
>>      case 0x401:
>>          /* used to be panic, now unused */
>>          break;
>> +#ifdef DEBUG_BIOS
>>      case 0x402:
>>      case 0x403:
>> -#ifdef DEBUG_BIOS
>>          fprintf(stderr, "%c", val);
>> -#endif
>>          break;
>> +#endif
>>      case 0x8900:
>>          /* same as Bochs power off */
>>          if (val == shutdown_str[shutdown_index]) {
> 
> 
> Is it possible to modify this part:
> 
>> @@ -598,8 +598,10 @@ static void *bochs_bios_init(void)
>>  
>>      register_ioport_write(0x400, 1, 2, bochs_bios_write, NULL);
>>      register_ioport_write(0x401, 1, 2, bochs_bios_write, NULL);
>> +#ifdef DEBUG_BIOS
>>      register_ioport_write(0x402, 1, 1, bochs_bios_write, NULL);
>>      register_ioport_write(0x403, 1, 1, bochs_bios_write, NULL);
>> +#endif
>>      register_ioport_write(0x8900, 1, 1, bochs_bios_write, NULL);
>>  
>>      register_ioport_write(0x501, 1, 1, bochs_bios_write, NULL);
> 
> 
> by something like that:
> 
> --------------------------
> @@ -592,7 +592,9 @@ int e820_add_entry(uint64_t address, uint64_t length, uint32_t type)
>  
>  static const MemoryRegionPortio bochs_bios_portio_list[] = {
>      { 0x400, 2, 2, .write = bochs_bios_write, }, /* 0x400 */
> +#ifdef DEBUG_BIOS
>      { 0x402, 2, 1, .write = bochs_bios_write, }, /* 0x402 */
> +#endif
>      { 0x500, 1, 1, .write = bochs_bios_write, }, /* 0x500 */
>      { 0x501, 1, 1, .write = bochs_bios_write, }, /* 0x501 */
>      { 0x501, 2, 2, .write = bochs_bios_write, }, /* 0x501 */
> 
> ---------------------------
> So it can be applied just after: "memory: unify ioport registration"
> patch series.Otherwise, I will modify my patch series.

No, lets do it again in an order that avoids temporal regressions,
specifically as autotests depend on debugcon.

Jan

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