[lldb-dev] Increasing support for other gdbservers

Vince Harron vince at nethacker.com
Tue Mar 31 16:36:44 PDT 2015

I hate ifdefs, especially the ones that we've added to the code. I would
hate to see any others go in.  It's our plan for example to remove ifdefs
that we have added .
On Mar 31, 2015 4:28 PM, "Zachary Turner" <zturner at google.com> wrote:

> As long as it's possible to build lldb without it I'm fine with whatever,
> including downloading it separately, building it, and referencing it
> externally.  But I don't want it to be a forced dependency.
> On Tue, Mar 31, 2015 at 4:19 PM Vince Harron <vince at nethacker.com> wrote:
>> I really don't want LLDB to embed a copy of libxml2.  I think we should
>> build it externally and reference it from LLDB.  Systems with package
>> managers can get this trivially.  Windows can download and build all
>> dependencies with one script.
>> On Mar 31, 2015 2:10 PM, "Colin Riley" <colin at codeplay.com> wrote:
>>>  I noticed that use in cmake also. FWIW, my primary LLDB platform is
>>> Windows, which is why we were using TinyXML2 for ease of prototyping. If
>>> libxml2 works on all the targets we will use it - I do worry about the
>>> usual issues you get with windows prebuilts. So source may still be
>>> required. We'll look into it.
>>> Colin
>>> On 31/03/2015 20:45, Zachary Turner wrote:
>>> There's already some stuff in the CMake to try to find libxml, but it's
>>> behind a Darwin specific branch in the CMake.  So I think what would need
>>> to happen is that we move this into a platform agnostic codepath, and then
>>> set a define like LLDB_HAVE_LIBXML2 in the code to a value that indicates
>>> whether it is present (search clang for CLANG_HAVE_LIBXML in *.* to see how
>>> this is done).  Then, in the code, we would need to put xml code behind a
>>> check for this define.
>>> On Tue, Mar 31, 2015 at 10:02 AM Zachary Turner <zturner at google.com>
>>> wrote:
>>>> A good rule of thumb for anything is that "Windows doesn't have it" and
>>>> that holds true for libxml2 as well.  It appears that libxml2 does support
>>>> Windows though (http://xmlsoft.org/downloads.html), it just isn't
>>>> something that's there by default.  It would be nice if everyone were using
>>>> the same thing, could we clone this repo in our own repo and then just
>>>> build it ourselves as part of the build process.  The license looks very
>>>> permissive, but IANAL.
>>>> On Tue, Mar 31, 2015 at 9:47 AM Greg Clayton <gclayton at apple.com>
>>>> wrote:
>>>>> > On Mar 31, 2015, at 3:35 AM, Aidan Dodds <aidan at codeplay.com> wrote:
>>>>> >
>>>>> > On 30/03/2015 18:38, Greg Clayton wrote:
>>>>> > >
>>>>> > > I know about the register numbering stuff and I would love to see
>>>>> support for the "$qXfer:features:" added to LLDB. The one thing this data
>>>>> doesn't contain is the register numbers for the ABI (DWARF register numbers
>>>>> (for debug info), compiler register numbers (for like .eh_frame)), but that
>>>>> info could be inferred from an ABI plugin that we could infer from the
>>>>> "osabi" of "GNU/Linux" in the target.xml:
>>>>> >
>>>>> > >
>>>>> > > So please do submit patches that implement this and we will be
>>>>> happy to approve them.
>>>>> >
>>>>> > I am currently prototyping $qXfer:features support in LLDB with an
>>>>> aim to upstream it. It will require an XML parser, so I wanted to have a
>>>>> discussion about adding one to LLDB.
>>>>> Most unix variants have libxml2 that is available. I am not sure on
>>>>> windows though. I have CC'ed Zachary to get some input on windows XML (in
>>>>> case LLVM doesn't already have some support for this).
>>>>> > I have been using TinyXML2 in my prototype, which is open sourced
>>>>> under the ZLib license. Is there any policy in LLDB for handling external
>>>>> library dependencies?
>>>>> > Would there be objections to TinyXML2 making its way into the LLDB
>>>>> code base as an external? Writing a new XML parser from scratch in LLDB
>>>>> isn't ideal.
>>>>> It would be great to stick with stuff that everyone has installed and
>>>>> hopefully that is libxml2. Windows is the biggest question. I am also not
>>>>> sure if llvm or clang has any XML support, but we should first look to see
>>>>> if llvm has XML support and if not, then look for alternatives. We
>>>>> definitely do not want to write our own.
>>>>> >
>>>>> > I would still like to have a discussion about adding a plugin
>>>>> architecture to gdb-remote making it easier to handle packets outwith the
>>>>> LLDB based servers. The code in gdb-remote that sends and handles packets
>>>>> is scattered over one or two huge classes, it would be beneficial to start
>>>>> looking at breaking this up and modularizing it. At least for the packets
>>>>> which are not supported by lldb's own RSP producers.
>>>>> I say just build all and any support it into
>>>>> GDBRemoteCommunicationClient and GDBRemoteCommunicationServer. I don't see
>>>>> the need to break it up.
>>>>> Greg Clayton
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