Re: Translate memory addresses

[Michael Eager <eager@eagerm.com>]

Mark Kettenis wrote:
>> Date: Tue, 08 Mar 2011 08:47:53 -0800
>> From: Michael Eager <eager@eagerm.com>
>>
>> Tom Tromey wrote:
>>>>>>>> "Michael" == Michael Eager <eager@eagerm.com> writes:
>>> Michael> I'm working with a target which needs to translate
>>> Michael> a virtual memory addresses to a physical address
>>> Michael> before accessing the target's memory or the core file.
>>>
>>> Michael> Core_ops is defined in corelow.c, and there doesn't appear
>>> Michael> to be an obvious hook for the target code to modify it to
>>> Michael> add the translation routine.
>>>
>>> Michael> Any suggestions on the best way to add a hook or how to specify
>>> Michael> a target routine to do address translations for core files?
>>>
>>> I am not an expert in this area, but couldn't you make a new
>>> arch_stratum target that does the translation?
>>>
>>> With this approach maybe you don't even need a hook -- just do the
>>> translation and call the target beneath.
>> Interesting idea.  I didn't think of adding a stratum for translation.
>>
>> I took a clue from the way that sol-thread.c prevents corelow.c
>> from calling add_target to install core_ops.  I added the following
>> to corelow.c:
>>
>>    CORE_ADDR (*target_translate_address) (struct target_ops *, CORE_ADDR addr);
>>
>> and in init_core_ops():
>>
>>    core_ops.to_translate_address = target_translate_address;
>>
>> The target code contains a definition for target_translate_address
>> which is initialized to point to the translation routine.  For other
>> targets, this will be zero.
>>
>> It's inelegant, what can I say, but functional.
> 
> Did you look at how the BSD kvm target does things?  It does a
> physical to virtual address translation (by using the system-provided
> libkvm), and seems to get away with this without having such a hook.

How would this help?  The kernel isn't running when debugging
a hardware target and you can't execute target code when debugging
a core file.


-- 
Michael Eager	 eager@eagercon.com
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