This is the mail archive of the
gdb-patches@sourceware.org
mailing list for the GDB project.
Re: [PATCH v10 04/10] Create empty common/linux-maps.[ch] and common/target-utils.[ch]
- From: Pedro Alves <palves at redhat dot com>
- To: Gary Benson <gbenson at redhat dot com>, Jan Kratochvil <jan dot kratochvil at redhat dot com>
- Cc: gdb-patches at sourceware dot org, Aleksandar Ristovski <ARistovski at qnx dot com>
- Date: Tue, 21 Jul 2015 11:28:50 +0100
- Subject: Re: [PATCH v10 04/10] Create empty common/linux-maps.[ch] and common/target-utils.[ch]
- Authentication-results: sourceware.org; auth=none
- References: <20150607200422 dot 8918 dot 48900 dot stgit at host1 dot jankratochvil dot net> <20150607200454 dot 8918 dot 52868 dot stgit at host1 dot jankratochvil dot net> <20150608083733 dot GA5405 at blade dot nx> <20150715212028 dot GA22133 at host1 dot jankratochvil dot net> <20150716081412 dot GA4954 at blade dot nx>
On 07/16/2015 09:14 AM, Gary Benson wrote:
> Jan Kratochvil wrote:
>> On Mon, 08 Jun 2015 10:37:33 +0200, Gary Benson wrote:
>>> A bunch of stuff has changed in the way common code is laid out
>>> since May 2014, so while Tom approved this back then, it's not
>>> suitable any more. Please update the series as follows:
>>>
>>>> * common/linux-maps.c: New file.
>>>> * common/linux-maps.h: New file.
>>>
>>> Nothing os-specific should be in common. These files should be
>>> nat/linux-maps.[ch].
>>
>> While I have done so I do not share this opinion. linux-maps.[ch]
>> is used from linux-tdep.c and not from linux-nat.c. linux-tdep.c is
>> using common/* files a lot but it uses no function from nat/*:
>>
>> $ for i in $(for i in common/*.c;do nm `basename $i .c`.o;done|sed -n 's/^.* T //p');do grep -q "\<$i (" linux-tdep.c && echo $i;done|wc -l
>> 17
>> $ for i in $(for i in nat/*.c;do nm `basename $i .c`.o;done|sed -n 's/^.* T //p');do grep -q "\<$i (" linux-tdep.c && echo $i;done|wc -l
>> 0
>> (commands above assume in-src-tree build)
>>
>> Additionally linux-maps.o should not be in config/**.mh::NATDEPFILES
>> (like linux-namespaces.o from nat/ ) but it needs to be in
>> configure.tgt instead.
>>
>> Should be linux-maps.[ch] therefore in nat/ or in common/ ?
>> If it matters, though.
>
> I don't fully understand the tdep/non-tdep split very well.
> Pedro, could you comment?
TL;DR: roughly, nat/ holds native target_ops code, while tdep
files hold gdbarch code.
The idea of nat/ is to hold host-dependent code that implements
the native target (target_ops) backends. Code in that directory makes use
of native system debug APIs, constants, etc.. Such code cannot be used
on a cross debugger that targets the OS the code is for, because it
e.g., relies on headers that will only exist on that target OS.
nat/ code is used by either gdb's native target_ops target, or, gdbserver's.
E.g., a --host=mingw32 --target=x86_64-linux gdb can't build the native
Linux code in nat/.
In contrast, the tdep files files contain code that _must_ be
host-independent. The same --host=mingw32 --target=x86_64-linux gdb
build includes the linux-specific -tdep files.
A -tdep.c file including a "nat/foo.h" header thus raises
the abstraction-violation alarm bell. It's at the same level of
a -tdep.c file including <sys/ptrace.h>.
So seems to me this maps code should not be in nat/.
Thanks,
Pedro Alves