Re: [Qemu-devel] [RFC] s390: dump-guest-memory implementation for s390x arch.

[Christian Borntraeger]

>>>> diff --git a/target-s390x/arch_memory_mapping.c 
>>>> b/target-s390x/arch_memory_mapping.c
>>>> new file mode 100644
>>>> index 0000000..3dad3b9
>>>> --- /dev/null
>>>> +++ b/target-s390x/arch_memory_mapping.c
>>>> @@ -0,0 +1,26 @@
>>>> +/*
>>>> + * s390x memory mapping
>>>> + *
>>>> + * Copyright IBM Corp. 2012
>>>> + *
>>>> + * Authors:
>>>> + *     Ekaterina Tumanova <address@hidden>
>>>> + *
>>>> + * This work is licensed under the terms of the GNU GPL, version 2 or 
>>>> later.
>>>> + * See the COPYING file in the top-level directory.
>>>> + *
>>>> + */
>>>> +
>>>> +#include "cpu.h"
>>>> +#include "exec/cpu-all.h"
>>>> +#include "sysemu/memory_mapping.h"
>>>> +
>>>> +int cpu_get_memory_mapping(MemoryMappingList *list, CPUArchState *env)
>>>> +{
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +bool cpu_paging_enabled(CPUArchState *env)
>>>> +{
>>>> +    return false;
>>>
>>> Why? :)
>>
>> To make things compile :-)
>> Why no paging? The idea was to have some code that allows getting an ELF 
>> dump of a Linux kernel.
>> All existing tooling for s390 expects real memory dumps. 
>>
>> Actually having CONFIG_HAVE_GET_MEMORY_MAPPING=n would be a sane thing todo, 
>> but IIRC the common
>> code in dump.c references some functions that are only available with 
>> CONFIG_HAVE_GET_MEMORY_MAPPING=y. 
>>
>> /home/cborntra/REPOS/qemu/dump.c:84: undefined reference to 
>> `memory_mapping_list_free'
>> dump.o: In function `dump_init':
>> /home/cborntra/REPOS/qemu/dump.c:753: undefined reference to 
>> `memory_mapping_list_init'
>> /home/cborntra/REPOS/qemu/dump.c:757: undefined reference to 
>> `qemu_get_guest_simple_memory_mapping'
>> /home/cborntra/REPOS/qemu/dump.c:761: undefined reference to 
>> `memory_mapping_filter'
> 
> It might be better to just fix those places and not claim that you can fetch 
> memory mappings then. QEMU has all the knowledge of s390 virtual memory you 
> would need to implement it. I can see how you wouldn't need it for core dumps 
> of the kernel, but it's confusing to claim dump support for VM and then say 
> you don't.
> 
> 
> Alex

So you suggest to implementing stubs for those 4 functions in 
memory_mapping-stub.c and see if dumping
of a kernel still works with CONFIG_HAVE_GET_MEMORY_MAPPING=n, right?

Christian