Re: [RFC PATCH v5 4/9] Add basic Linux kernel support

Kamil Rytarowski
2018-03-14T23:38:23Z

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On 14.03.2018 10:48, Philipp Rudo wrote:
> Hi Kamil,
>
> On Tue, 13 Mar 2018 15:08:32 +0100
> Kamil Rytarowski <n54@gmx.com> wrote:
>
>> On 12.03.2018 16:31, Philipp Rudo wrote:
>>> Implement the basic infrastructure and functionality to allow Linux kernel
>>> debugging with GDB. This contains handling of kernel symbols and data
>>> structures as well as a simple target_ops to hook into GDB. For the code
>>> to work architectures must provide an implementation for the virtual
>>> methods in linux_kernel_ops.
>>>
>>> For simplicity this patch only supports static targets, i.e. core dumps.
>>> Support for live debugging will be provided in a separate patch.
>>>
>>
>>
>> What's wrong with kgdb? It works well on NetBSD for alive and dead
>> kernels since 90ties.
>
> I don't know kgdb well. We at IBM mostly work with dumps and the crash tool,
> which is based on an old version of gdb and has some drawbacks. For example it
> doesn't have a dwarf unwinder. That's why we wanted to see if the logic needed
> for kernel debugging can be added directly to gdb, instead of having a hack
> working on top of it.
>
> Furthermore, I don't see a conflict between kgdb and this work. The way I see
> it, kgdb is a technique to retrieve information from the kernel. This work
> however, teaches gdb how to interpret the data from the kernel in order to make
> it easier to find the information you need.
>

I see. Once you will be done, I will have a look whether it can be
useful for other OSes.

I've mentioned kgdb, as it has been ported to Linux and it can work as a
backend for GDB.

> Thanks
> Philipp
>

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