Re: [PATCH 14/15] add a domU script to fetch overlays and applying them to linux

[Jan Beulich <jbeulich@xxxxxxxx>]

On 25.04.2024 02:54, Henry Wang wrote:
> On 4/24/2024 2:16 PM, Jan Beulich wrote:
>> On 24.04.2024 05:34, Henry Wang wrote:
>>> From: Vikram Garhwal <fnu.vikram@xxxxxxxxxx>
>>>
>>> Introduce a shell script that runs in the background and calls
>>> get_overlay to retrive overlays and add them (or remove them) to Linux
>>> device tree (running as a domU).
>>>
>>> Signed-off-by: Vikram Garhwal <fnu.vikram@xxxxxxxxxx>
>>> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
>>> Signed-off-by: Henry Wang <xin.wang2@xxxxxxx>
>>> ---
>>>   tools/helpers/Makefile       |  2 +-
>>>   tools/helpers/get_overlay.sh | 81 ++++++++++++++++++++++++++++++++++++
>>>   2 files changed, 82 insertions(+), 1 deletion(-)
>>>   create mode 100755 tools/helpers/get_overlay.sh
>> Besides the same naming issue as in the earlier patch, the script also
>> looks very Linux-ish. Yet ...
> 
> I will fix the naming issue in v2. Would you mind elaborating a bit more 
> about the "Linux-ish" concern? I guess this is because the original use 
> case is on Linux, should I do anything about this?

Well, the script won't work on other than Linux, will it? Therefore ...

>>> --- a/tools/helpers/Makefile
>>> +++ b/tools/helpers/Makefile
>>> @@ -58,7 +58,6 @@ init-dom0less: $(INIT_DOM0LESS_OBJS)
>>>   get_overlay: $(SHARE_OVERLAY_OBJS)
>>>     $(CC) $(LDFLAGS) -o $@ $< $(LDLIBS_libxenvchan) $(LDLIBS_libxenstore) 
>>> $(LDLIBS_libxenctrl) $(LDLIBS_libxengnttab) $(APPEND_LDFLAGS)
>>>   
>>> -
>>>   .PHONY: install
>>>   install: all
>>>     $(INSTALL_DIR) $(DESTDIR)$(LIBEXEC_BIN)
>>> @@ -67,6 +66,7 @@ install: all
>>>   .PHONY: uninstall
>>>   uninstall:
>>>     for i in $(TARGETS); do rm -f $(DESTDIR)$(LIBEXEC_BIN)/$$i; done
>>> +   $(RM) $(DESTDIR)$(LIBEXEC_BIN)/get_overlay.sh
>>>   
>>>   .PHONY: clean
>>>   clean:
>> ... you touching only the uninstall target, it's not even clear to me
>> how (and under what conditions) the script is going to make it into
>> $(DESTDIR)$(LIBEXEC_BIN)/. Did you mean to add to $(TARGETS), perhaps,
>> alongside the earlier added get-overlay binary?

... it first of needs to become clear under what conditions it is actually
going to be installed.

> You are right, I think the get-overlay binary and this script should be 
> installed if DTB overlay is supported. Checking the code, I found 
> LIBXL_HAVE_DT_OVERLAY which can indicate if we have this feature 
> supported in libxl. Do you think it is a good idea to use it to install 
> these two files in Makefile? Thanks.

Counter question: If it's not going to be installed, how are people going
to make use of it? If the script is intended for manual use only, I think
that would want saying in the description. Yet then I couldn't see why
the uninstall goal would need modifying.

As to LIBXL_HAVE_DT_OVERLAY - that's not accessible from a Makefile, I
guess?

Jan