Re: [Qemu-devel] [RFC][PATCH 05/16 v6] Add API to get memory mapping

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

On 2012-02-09 04:22, Wen Congyang wrote:
> Add API to get all virtual address and physical address mapping.
> If there is no virtual address for some physical address, the virtual
> address is 0.
> 
> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> ---
>  memory_mapping.c |   65 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  memory_mapping.h |    1 +
>  2 files changed, 66 insertions(+), 0 deletions(-)
> 
> diff --git a/memory_mapping.c b/memory_mapping.c
> index d83b7d7..fc0ddee 100644
> --- a/memory_mapping.c
> +++ b/memory_mapping.c
> @@ -128,3 +128,68 @@ void free_memory_mapping_list(MemoryMappingList *list)
>  
>      list->num = 0;
>  }
> +
> +void get_memory_mapping(MemoryMappingList *list)
> +{
> +    CPUState *env;
> +    MemoryMapping *memory_mapping;
> +    RAMBlock *block;
> +    ram_addr_t offset, length;
> +
> +    last_mapping = NULL;
> +
> +    for (env = first_cpu; env != NULL; env = env->next_cpu) {
> +        cpu_get_memory_mapping(list, env);

Hmm, is the CPU number recorded along with the mappings? I mean, how
could crash tell them apart afterward if they are contradictory? This
way, they are just thrown in the same bucket, correct?

Even if crash or gdb aren't prepared for cpu/thread-specific mappings,
could we already record that information for later use? Or would it
break compatibility with current versions?

> +    }
> +
> +    /* some memory may be not mapped, add them into memory mapping's list */
> +    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;

Please avoid redundant returns.

> +}
> diff --git a/memory_mapping.h b/memory_mapping.h
> index a4b1532..679f9ef 100644
> --- a/memory_mapping.h
> +++ b/memory_mapping.h
> @@ -34,5 +34,6 @@ void add_to_memory_mapping(MemoryMappingList *list,
>                             ram_addr_t length);
>  
>  void free_memory_mapping_list(MemoryMappingList *list);
> +void get_memory_mapping(MemoryMappingList *list);
>  
>  #endif

Maybe [qemu_]get_guest_memory_mapping. Just get_memory_mapping sounds a
bit to generic to me. Could be any mapping.

Jan

-- 
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux