Add a section for Samsung system-as-root A-only devices.
Change-Id: Ia7f033f20c2fac248edb3c007998b6003ae04ec1
diff --git a/_includes/samsungsystemasroot.html b/_includes/samsungsystemasroot.html
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+<div class='page-heading'>This device uses system-as-root in an A-only partition configuration.</div>
+<hr />
+
+<p class="text">If you intend to root your ({{ page.codename }}) device, you need to be aware that Magisk will be installed to the <tt>recovery</tt> partition, not the usual <tt>boot</tt> partition. Both TWRP and Magisk-rooted Android boot using the recovery kernel, and the device's hardware keys are used to choose between TWRP and Android at boot time.</p>
+
+<p class"text"> You are therefore strongly advised to pre-root a TWRP image before flashing it to recovery. The more common route of installing TWRP prior to rooting is problematic on this device, because the Magisk installer does not support installation to recovery from TWRP.</p>
+
+<p class="text">If you wish to install TWRP without rooting, there are other pitfalls to consider. For example, a stock device is protected by a <tt>vbmeta</tt> partition that contains cryptographic digests for verifying the integrity of <tt>boot.img</tt>, <tt>recovery.img</tt> and other partitions/images. Flashing TWRP without first flashing an empty <tt>vbmeta</tt> image to disable this verification will render your device unable to boot.</p>
+
+<p class="text">Please bear all of the above in mind when considering the installation methods listed below, and refer to the device's TWRP support thread on XDA for detailed information about installation and the associated hazards. Details of the firmware version(s) with which the current TWRP image's kernel is compatible can be found in the TWRP changelog for this device.</p>