Re: [Qemu-devel] [RFC][PATCH 04/14 v7] Add API to get memory mapping

[Wen Congyang <wency@cn.fujitsu.com>]

At 03/01/2012 02:01 PM, HATAYAMA Daisuke Wrote:
> From: Wen Congyang <wency@cn.fujitsu.com>
> Subject: [RFC][PATCH 04/14 v7] Add API to get memory mapping
> Date: Thu, 01 Mar 2012 10:43:13 +0800
> 
>> +int qemu_get_guest_memory_mapping(MemoryMappingList *list)
>> +{
>> +    CPUState *env;
>> +    MemoryMapping *memory_mapping;
>> +    RAMBlock *block;
>> +    ram_addr_t offset, length;
>> +    int ret;
>> +
>> +#if defined(CONFIG_HAVE_GET_MEMORY_MAPPING)
>> +    for (env = first_cpu; env != NULL; env = env->next_cpu) {
>> +        ret = cpu_get_memory_mapping(list, env);
>> +        if (ret < 0) {
>> +            return -1;
>> +        }
>> +    }
>> +#else
>> +    return -2;
>> +#endif
>> +
>> +    /* some memory may be not mapped, add them into memory mapping's list */
> 
> The part from here is logic fully for 2nd kernel? If so, I think it
> better to describe why this addtional mapping is needed; we should
> assume most people doesn't know kdump mechanism.

Not only for 2nd kernel. If the guest has 1 vcpu, and is in the 2nd kernel,
we need this logic for 1st kernel.

Thanks
Wen Congyang

> 
>> +    QLIST_FOREACH(block, &ram_list.blocks, next) {
>> +        offset = block->offset;
>> +        length = block->length;
>> +
>> +        QTAILQ_FOREACH(memory_mapping, &list->head, next) {
>> +            if (memory_mapping->phys_addr >= (offset + length)) {
>> +                /*
>> +                 * memory_mapping's list does not conatin the region
>> +                 * [offset, offset+length)
>> +                 */
>> +                create_new_memory_mapping(list, offset, 0, length);
>> +                length = 0;
>> +                break;
>> +            }
>> +
>> +            if ((memory_mapping->phys_addr + memory_mapping->length) <=
>> +                offset) {
>> +                continue;
>> +            }
>> +
>> +            if (memory_mapping->phys_addr > offset) {
>> +                /*
>> +                 * memory_mapping's list does not conatin the region
>> +                 * [offset, memory_mapping->phys_addr)
>> +                 */
>> +                create_new_memory_mapping(list, offset, 0,
>> +                                          memory_mapping->phys_addr - offset);
>> +            }
>> +
>> +            if ((offset + length) <=
>> +                (memory_mapping->phys_addr + memory_mapping->length)) {
>> +                length = 0;
>> +                break;
>> +            }
>> +            length -= memory_mapping->phys_addr + memory_mapping->length -
>> +                      offset;
>> +            offset = memory_mapping->phys_addr + memory_mapping->length;
>> +        }
>> +
>> +        if (length > 0) {
>> +            /*
>> +             * memory_mapping's list does not conatin the region
>> +             * [offset, memory_mapping->phys_addr)
>> +             */
>> +            create_new_memory_mapping(list, offset, 0, length);
>> +        }
>> +    }
>> +
>> +    return 0;
>> +}
> 
> I think it more readable if shortening memory_mapping->phys_addr and
> memmory_maping->length at the berinning of the innermost foreach loop.
> 
>   m_phys_addr = memory_mapping->phys_addr;
>   m_length = memory_mapping->length;
> 
> Then, each conditionals becomes compact.
> 
> Thanks.
> HATAYAMA, Daisuke
> 
>