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<p> Hi Petr,<br>
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<div id="smartTemplate4-quoteHeader">-------- Original Message --------<br>
From: Petr Vorel<br>
Sent: Fri, 12 Apr 2019 01:40:42 +0200<br>
To: Sandeep Patil<br>
Cc: Ltp<br>
Subject: Re: [LTP] 回复：[PATCH v1] include/mk/env_post.mk: enable
__ANDROID__ definition for Android b uild<br>
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<blockquote type="cite" cite="mid:20190411234041.GB381@x230">
<pre class="moz-quote-pre" wrap="">Hi Sandeep,
</pre>
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<pre class="moz-quote-pre" wrap="">-CFLAGS += -Werror-implicit-function-declaration
+CFLAGS += -Werror-implicit-function-declaration -D__ANDROID__
</pre>
</blockquote>
<pre class="moz-quote-pre" wrap="">Would adding __ANDROID__ definition help building LTP with distro
cross-compiler? (i.e. no NDK, no inside AOSP tree)?
I guess so and therefore, I'd be for this change.
I see some projects added it as well (busybox [1] [2], dnsmasq [3]).
BTW: where is defined for AOSP and NDK?
</pre>
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</pre>
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<pre class="moz-quote-pre" wrap="">I think I've used __ANDROID__ and __BIONIC__ in the past for android-specific
things. Honestly, I haven't tried to build for Android outside of AOSP tree
yet. I am happy to test this if you tell me how? (sorry for that.)
</pre>
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<pre class="moz-quote-pre" wrap="">Great, thanks a lot!
</pre>
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<pre class="moz-quote-pre" wrap="">According to [1] android toolchain (I guess both AOSP and NDK toolchain) define
__ANDROID__. Which is what I'd expect.
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<pre class="moz-quote-pre" wrap="">Grepping aosp only dnsmasq and swiftshader use -D__ANDROID__ (these are from
externals). -DANDROID is use more times (e.g. some drivers in hardware - ril,
qcom, libsensors and wpa_supplicant).
</pre>
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<pre class="moz-quote-pre" wrap="">From my point of view, instead of -D__ANDROID__ or -DANDROID I'd prefer to to have
proper #ifdef HAVE_FOO guarders made by autotools checks. As android is not the
only minor libc. But I understand it's not always possible and we already use
some #ifdef __ANDROID__ in library sources and headers, so ack from myself to
help compilation outside AOSP and without NDK.
</pre>
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<pre class="moz-quote-pre" wrap="">Actually I was wrong. 1) I was using NDK toolchain. I'd expect it'd generate
__ANDROID__, but I don't see it in the output. 2) Building for android with
distro toolchain doesn't make sense as it wouldn't have Bionic.</pre>
</blockquote>
<p>1) Did you build outside AOSP? If so, I think it is reasonable
since whatever __ANDROID__ or ANDROID are defined by Android build
system instead of toolchain. I also tried to build the external/*
thing and found ANDROID was actually generated. In my test,
ANDROID seems to be the more suitable one, but in fact we can not
build ltp inside AOSP because there is no Android.mk in ltp
(please correct me if I am wrong...), so ANDROID is meaningless
to us here. Actually, this is why I think this patch is still
useful, since __ANDROID__ is enough to distinguish what to compile
if ANDROID=1 is set with make.<br>
</p>
<p>2) In the case of cross-compilation, I think it still makes
sense, since we can use the same toolchain, such as clang, and
build parameters (the specify the include headers and libs, etc)
as AOSP. This is what I am doing now, you can see my steps I
posted in my previous reply. But in this case, we need to
obviously set -D__ANDROID__ in CFLAGS. After that , the process
should be similar as we launch a build inside AOSP.</p>
<p><br>
</p>
<p>Regards,</p>
<p>Zhengwang<br>
</p>
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Kind regards,
Petr
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