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14 <h1>The rEFInd Boot Manager:<br />Using EFI Drivers</h1>
15
16 <p class="subhead">by Roderick W. Smith, <a
17 href="mailto:rodsmith@rodsbooks.com">rodsmith@rodsbooks.com</a></p>
18
19 <p>Originally written: 4/19/2012; last Web page update:
20 9/19/2015, referencing rEFInd 0.9.2</p>
21
22
23 <p>This Web page is provided free of charge and with no annoying outside ads; however, I did take time to prepare it, and Web hosting does cost money. If you find this Web page useful, please consider making a small donation to help keep this site up and running. Thanks!</p>
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127 <hr />
128
129 <p>This page is part of the documentation for the rEFInd boot manager. If a Web search has brought you here, you may want to start at the <a href="index.html">main page.</a></p>
130
131 <hr />
132
133 <div style="float:right; width:55%">
134
135 <p>Beginning with version 0.2.7, rEFInd has been able to load EFI drivers, and as of version 0.4.0, it has shipped with some EFI filesystem drivers. Although EFI implementations should be able to load drivers prior to rEFInd's launch, in my experience, most EFI implementations offer such poor control over EFI driver loading that they can't be counted on to do this. Thus, if you want to use EFI drivers, rEFInd's ability to do so can be useful. This page tells you why you might want to use drivers, how you can install and use rEFInd's own drivers, where you can go to find other drivers, and provides tips on a few specific drivers.</p>
136
137 </div>
138
139 <div class="navbar">
140
141 <h4 class="tight">Contents</h4>
142
143 <ul>
144
145 <li class="tight"><a href="#why">Why Should You Use Drivers?</li>
146
147 <li class="tight"><a href="#using">Using rEFInd's EFI Drivers</a></li>
148
149 <li class="tight"><a href="#finding">Finding Additional Drivers</a></li>
150
151 <li class="tight"><a href="#notes">Notes on Specific Drivers</a></li>
152
153 </ul>
154
155 </div>
156
157 <br/>
158 <a name="why">
159 <h2>Why Should You Use EFI Drivers?</h2>
160 </a>
161
162 <p>EFI supports drivers, which can activate hardware or filesystems in the pre-boot environment. At the moment, EFI drivers are few and far between; but you can or might want to use them for various reasons:</p>
163
164 <ul>
165
166 <!-- <p class="sidebar"><b>Tip:</b> Some Linux installation media come as <i>hybrid ISO</i> files, which can be written to either optical discs or USB flash drives for installation. Some of these media, though, are useless for installing to EFI systems from USB flash drives&mdash;unless your computer supports ISO-9660 on non-optical media. rEFInd's ISO-9660 driver provides this support. To use such a hybrid image from USB flash drive, you must boot using rEFInd on another disk that has the ISO-9660 driver installed. rEFInd should then provide an option to boot from the USB flash drive. I cannot guarantee that the installer will boot at this point, but it might.</p> -->
167
168 <li>You can load a filesystem driver to gain access to files on a filesystem other than FAT (or HFS+ on Macs or ISO-9660 on some systems). This is most likely to be useful on a Linux installation, since a filesystem driver can enable you to store a Linux kernel with EFI stub loader or for use by ELILO on a Linux-native filesystem if your EFI System Partition (ESP) is getting crowded.</li>
169
170 <li>You can load a driver for a plug-in disk controller to give the EFI access to its disks. Note that this is <i>not</i> required if you place your boot loader (and perhaps your OS kernel) on another disk, or if the plug-in disk controller includes EFI-capable firmware. It could be handy, perhaps in conjunction with a filesystem driver, to enable the EFI to read a boot loader or kernel from a disk on a plug-in controller, though.</li>
171
172 <li>You can load a driver for a plug-in network card to enable the computer to boot from the network, or to access the network without booting an OS. Note that rEFInd does not currently support network boots itself, though.</li>
173
174 <li>You can load a video card driver to set an appropriate video mode or to support a plug-in card that lacks EFI support in ts own firmware.</li>
175
176 </ul>
177
178 <p>Note that most of these uses are theoretical, at least to me; I don't know of any specific examples of EFI drivers (available as separate files) for disk controller hardware, network cards, or video cards. Such drivers are often embedded in the firmware of the devices themselves, and should be loaded automatically by the EFI. Chances are good that a few such drivers are available, unknown to me, and more may become available in the future. If you happen to have a device and need support for it under EFI, searching for drivers is certainly worth doing.</p>
179
180 <p>To the best of my knowledge, the best reason to want EFI driver support in rEFInd is to provide access to filesystems. Although EFI filesystem driver choices are currently somewhat limited, those that are available can help to improve your installation and configuration options, particularly if you've found yourself "boxed in" by awkward installation or bugs, such as the dinky ESP that Ubuntu creates by default or the bug that prevents a Linux kernel with <a href="http://www.rodsbooks.com/efi-bootloaders/efistub.html">EFI stub loader support</a> from booting from the ESP of at least some Macs.</p>
181
182 <p>As a side note, using an ISO-9660 driver can theoretically help you keep the size of a custom Linux boot CD/DVD down to a reasonable value. This is because EFI systems normally boot from optical discs by reading a FAT image file in El Torito format and treating that file as an ESP. If you need to store the kernel both in that file and directly in the ISO-9660 filesystem (to maintain bootability on BIOS systems), that can represent an unwanted extra space requirement. Placing rEFInd and an ISO-9660 driver in the FAT image file should enable you to store the kernel on the disc only once. Unfortunately, this doesn't work in practice. When the ISO-9660 driver is loaded from the El Torito image, the driver discovers that the optical disc is in use and refuses to access it. It's possible to use EFI shell commands to give the ISO-9660 driver access to the shell device, but this causes the El Torito access to go away, which means that anything loaded from the El Torito image (such as rEFInd) is likely to malfunction. Also, some EFI implementations include ISO-9660 drivers, so you might not need a separate ISO-9660 driver if you're building a disc for a particular computer.</p>
183
184 <a name="using">
185 <h2>Using rEFInd's EFI Drivers</h2>
186 </a>
187
188 <p class="sidebar"><b>Note:</b> If you want to use the drivers with a Mac, be sure to use at least version 0.4.3. Earlier versions were incompatible with the Mac's EFI 1.x firmware. Alternatively, you can use the drivers that came with <a href="http://refit.sourceforge.net">rEFIt,</a> which work on Macs.</p>
189
190 <p>Since version 0.4.0, rEFInd has shipped with a small collection of read-only EFI filesystem drivers. These are:</p>
191
192 <ul>
193
194 <li><b>ReiserFS</b>&mdash;This driver originated with rEFIt. It's useful
195 for reading Linux kernels from a separate <tt>/boot</tt> partition, or
196 even from a root (<tt>/</tt>) filesystem, if you use ReiserFS on it.
197 <b>Caution:</b> If you use this driver, you should use the
198 <tt>notail</tt> option in Linux's <tt>/etc/fstab</tt> file for the
199 partition(s) you want the EFI to read. This is because the driver
200 doesn't properly handle ReiserFS's "tail-packing" feature, so files can
201 seem to be corrupted in EFI if you use this feature, which is disabled
202 by <tt>notail</tt>.</li>
203
204 <li><b>Ext2fs</b>&mdash;This driver also originated with rEFIt. It can be
205 used in the same way as the ReiserFS driver. Although it's called an
206 "ext2fs" driver, it also works with ext3fs.</li>
207
208 <li><b>Ext4fs</b>&mdash;Stefan Agner <a
209 href="https://github.com/falstaff84/rEFInd">modified the rEFIt/rEFInd
210 ext2fs driver</a> so that it could handle ext4fs. I'm including this as
211 a separate driver from the ext2fs driver, although the ext4fs version
212 can handle ext2fs and ext3fs, too. Providing both drivers enables
213 easy filesystem separation&mdash;for instance, you can use ext2fs on a
214 <tt>/boot</tt> partition and ext4fs on your root (<tt>/</tt>)
215 partition, to have the EFI scan only the former. This driver has some
216 limitations. Most notably, for various reasons it maxes out at 16TiB
217 and won't mount any ext4 filesystem that's larger than this. As of
218 version 0.6.1, this driver supports the <tt>meta_bg</tt> feature, which
219 can also be used on ext2fs and ext3fs. Thus, it can handle some ext2fs
220 and ext3fs partitions that the ext2fs driver can't handle. You can
221 learn about your ext2/3/4 filesystem features by typing <tt
222 class="userinput">dumpe2fs <i>/dev/sda2</i> | grep features</tt>,
223 changing <tt class="userinput"><i>/dev/sda2</i></tt> to your
224 filesystem's device.</li>
225
226 <li><b>Btrfs</b>&mdash;</b>Samuel Liao contributed this driver, which is
227 based on the rEFIt/rEFInd driver framework and algorithms from the GRUB
228 2.0 Btrfs driver. I've tested this driver with a simple one-partition
229 filesystem and with a filesystem that spans two physical devices
230 (although I've made no attempt to ensure that the driver can actually
231 read files written to both devices). Samuel Liao has used the driver
232 with a compressed Btrfs volume. The driver will handle subvolumes, but
233 you may need to add kernel options if you're booting a Linux kernel
234 directly from a filesystem that uses subvolumes. For instance, on a
235 test installation of Ubuntu 14.04 alpha on such a system, I needed to
236 set <tt>also_scan_dirs + @/boot</tt> in <tt>refind.conf</tt> and add
237 <tt>rootflags=subvol=@</tt> to the kernel options in my
238 <tt>refind_linux.conf</tt> file. Without the first of these options,
239 rEFInd could not locate my kernel; and without the second, the boot
240 failed with a message to the effect that the initial RAM disk could not
241 find <tt>/sbin/init</tt>.</li>
242
243 <li><b>ISO-9660</b>&mdash;This driver originated with rEFIt's author, but
244 he never released a final version. Its code was improved by Oracle for
245 use in its VirtualBox product, and then further modified by the authors
246 of the <a
247 href="https://sourceforge.net/projects/cloverefiboot/">Clover</a> boot
248 loader. If your firmware doesn't provide its own ISO-9660 driver, this
249 one can be helpful; however, you may need to install it on your hard
250 disk before you can read an optical disc.</li>
251
252 <li><b>HFS+</b>&mdash;Oracle seems to have written this driver, apparently
253 with some code taken from open source Apple examples. It was then
254 further modified by the Clover authors. I expect this driver to have
255 limited appeal to most rEFInd users. Macs don't need it, since Apple's EFI
256 implementation provides its own HFS+ driver, and HFS+ isn't normally
257 used on UEFI-based PCs. Some CDs are mastered with both ISO-9660 and
258 HFS+, or even with HFS+ alone, and it's conceivable that an HFS+ driver
259 would be useful when accessing such discs. I'm providing the driver
260 mainly because it compiled cleanly with no extra work, aside from
261 providing a Makefile entry for it.</li>
262
263 <p class="sidebar"><b>Warning:</b> I've received multiple reports of system hangs when using the NTFS driver; however, I've been unable to replicate the problem. (The problem is probably triggered either by interactions with specific EFIs or by unique features of the "problem" NTFS volumes.) I therefore recommend avoiding it unless it's absolutely necessary. I've added a couple of checks to the driver code in rEFInd 0.9.1 that <i>may</i> fix this problem, but these checks may also have no effect.</p>
264
265 <li><b>NTFS</b>&mdash;Samuel Liao contributed this driver, which uses the
266 rEFIt/rEFInd driver framework. Note that this driver is
267 <i><b>not</b></i> required to boot Windows with rEFInd, since Windows
268 stores its EFI boot loader on the (FAT) ESP, and the BIOS boot process
269 (generally used when dual-booting on a Mac) relies only on the
270 partition's boot sector, which is read without the benefit of this
271 driver. Reasons to use this driver include:
272 <ul>
273 <li>If you want to store large boot files to be read from EFI, such as
274 RAM disk images, from Windows.</li>
275 <li>If you have a Mac and NTFS data partitions, loading this driver
276 should exclude those data partitions from the boot menu.</li>
277 <li>If you have a Mac that dual-boots with Windows, using this driver
278 should provide NTFS volume names in the boot menu.</li>
279 </ul>
280 </li>
281
282 </ul>
283
284 <p>All of these drivers rely on filesystem wrapper code written by rEFIt's author, Christoph Phisterer.</p>
285
286 <p class="sidebar"><b>Note:</b> rEFInd's <tt>refind-install</tt> script, when run from Linux, installs the driver required to read the <tt>/boot</tt> directory. Under OS X, the <tt>refind-install</tt> script installs the ext4fs driver if the script detects a Linux partition&mdash;but you might need to change this driver if you use another filesystem. The script installs all the available drivers if you pass it the <tt>--alldrivers</tt> option. (I do <i>not</i> recommend using this feature except for creating general-purpose USB flash drives with rEFInd, since having too many drivers can cause various problems.) See the <a href="installing.html">Installing rEFInd</a> page for details.</p>
287
288 <p>If you want to use one or more of these drivers, you can install them from the rEFInd binary package from the <tt>refind/drivers_<tt class="variable">arch</tt></tt> directory, where <tt class="variable">arch</tt> is a CPU architecture code&mdash;<tt>x64</tt> or <tt>ia32</tt>. The files are named after the filesystems they handle, such as <tt>ext4_x64.efi</tt> for the 64-bit ext4fs driver. You should copy the files for the filesystems you want to use to the <tt>drivers</tt> or <tt>drivers_<tt class="variable">arch</tt></tt> subdirectory of the main rEFInd installation directory. (You may need to create this subdirectory.) Be careful to install drivers only for your own architecture. Attempting to load drivers for the wrong CPU type will cause a small delay at best, or may cause the computer to crash at worst. I've placed rEFInd's drivers in directories that are named to minimize this risk, but you should exercise care when copying driver files.</p>
289
290 <p class="sidebar"><b>Warning:</b> <i>Do not</i> place EFI program files in your driver directories! Unfortunately, EFI uses the same <tt>.efi</tt> filename extension to identify both EFI program files and EFI drivers. Therefore, rEFInd can't distinguish between the two prior to loading them, and if you place program files in a drivers directory, rEFInd will run the EFI program file when it does its driver scan.</p>
291
292 <p>When you reboot after installing drivers, rEFInd should automatically detect and use the drivers you install. There's likely to be an extra delay, typically from one to five seconds, as rEFInd loads the drivers and tells the EFI to detect the filesystems they handle. For this reason, and because of the possibility of drivers harboring bugs, I recommend installing only those drivers that you need. If you like, you can install drivers you don't plan on using to some other directory, such as <tt>/drivers</tt> on the ESP's root. You can then load these drivers manually with the EFI shell's <tt>load</tt> command if the need arises in the future. You can then tell the shell to re-assign drive identifiers with <tt>map -r</tt>:</p>
293
294 <pre class="listing">
295 fs0: <tt class="userinput">load reiserfs_x64.efi</tt>
296 fs0: <tt class="userinput">map -r</tt>
297 </pre>
298
299 <a name="finding">
300 <h2>Finding Additional EFI Drivers</h2>
301 </a>
302
303 <p>As already noted, I know of no EFI drivers for EFI hardware, aside from those that are built into motherboards' EFI implementations. I do, however, know of a few EFI filesystem drivers, in addition to those provided with rEFInd:</p>
304
305 <ul>
306
307 <li><b><a href="http://efi.akeo.ie">Pete Batard's efifs drivers</a></b>&mdash;This project is an EFI driver wrapper around GRUB 2's filesystem drivers. Once compiled, the result is that GRUB 2's drivers become standalone EFI filesystem drivers, loadable independently or by rEFInd. (rEFInd version 0.8.3 or later is required.) At present (driver version 0.7; January 2015), several drivers, including NTFS, exFAT, ext2fs, ReiserFS, Btrfs, JFS, and XFS, are usable, albeit with some caveats. Some drivers are slow, and they hang on some computers, such as one of my Macs. I have no doubt that these drivers will improve rapidly in usability in the near future. Note that the ext2fs driver from this set works with ext3fs and ext4fs, too. In addition to the main link, you can check the <a href="https://github.com/pbatard/efifs">github repository</a> for the source code.</li>
308
309 <li><b><a href="http://refit.sourceforge.net">rEFIt's ext2fs and ReiserFS drivers</a></b>&mdash;You can gain read-only access to ext2fs, ext3fs, and ReiserFS volumes with these drivers, originally written by Christoph Pfisterer. You can use the binaries in the <tt>refit-bin-0.14/efi/tools/drivers</tt> directory of the binary package directly on a Mac. On a UEFI-based PC, though, you'll need to break the Mac-style "fat" binary into its 32- and 64-bit components. You can use my <a href="http://www.rodsbooks.com/thin/index.html"><tt>thin</tt></a> program for this job. As a practical matter, there's no advantage to using these drivers over rEFInd's drivers, since the latter are updated versions of the former.</li>
310
311 <li><b><a href="https://sourceforge.net/projects/cloverefiboot/">Clover EFI's ISO-9660, ext2fs, ext4fs, and HFS+ drivers</a></b>&mdash;This project is an offshoot of TianoCore, the main UEFI project. It's primarily a Hackintosh boot loader, but it includes drivers for <a href="http://cloverefiboot.svn.sourceforge.net/viewvc/cloverefiboot/VBoxFsDxe/">ISO-9660, ext2fs, ext4fs, and HFS+;</a> however, building them requires a fair amount of expertise. These drivers served as a starting point for rEFInd's drivers, except for the ext4fs driver, which the Clover developers based on rEFInd's ext4fs driver. Thus, as with the rEFIt drivers, there's likely to be no advantage to using the Clover drivers over the rEFInd drivers.</li>
312
313 <li><b><a href="http://www.osx86.net/view/2571-clover_v2_r384__efi_bootloader_pkg_+_gpt_efi_tools.html">Clover's EFI Tools package</a></b>&mdash;This osx86.net thread includes links to a package called <tt> EFI_Tools_Clover_v2_r1888_EN.zip</tt>, which holds an OS X application (a directory with a <tt>.app</tt> extension, as seen from other platforms) with a number of drivers in the <tt>Contents/Resources/EFI/drivers64</tt> directory (and an equivalent for 32-bit binaries). Some of these, such as keyboard drivers, are unlikely to be useful unless your system is badly broken as delivered. Three that caught my eye, however, are <tt>VBoxExt2-64.efi</tt>, <tt>VBoxIso9600-64.efi</tt>, and <tt>NTFS-64.efi</tt>. The first two of those are presumably variants on rEFInd's drivers, but the NTFS driver is not. I don't know this driver's provenance, so I'm reluctant to recommend its use, but it bears mentioning.</li>
314
315 <li><b><a href="https://www.virtualbox.org/browser/vbox/trunk/src/VBox/Devices/EFI/Firmware2/VBoxPkg/VBoxFsDxe">VirtualBox's HFS+ and ISO-9660 drivers</a></b>&mdash;These drivers are available in source code form, and come with VirtualBox binaries. I've not attempted to compile them myself, but I've seen a report that suggests they may include assumptions that require use of <a href="http://www.mingw.org/">MinGW,</a> a GCC-based compiler for Windows (and cross-compiler to build Windows executables under Linux). I don't know of a source for binaries suitable for use on EFI-based computers; if you want to use them, you'll need to figure out how to compile them yourself. As noted earlier, rEFInd's drivers are closely related to these.</li>
316
317 <li><b>Ext2Pkg</b>&mdash;This driver, based on <a href="https://bitbucket.org/alinrus/ext2pkg">bitbucket</a> and with a backup on <a href="https://github.com/the-ridikulus-rat/Tianocore_Ext2Pkg">github,</a> appears to be an ext2fs/ext3fs driver built independently of the driver written by Christoph Pfisterer. The linked-to sites provide access to source code via <tt>git</tt> but do not provide binaries. When I built binaries, they failed to work. Under VirtualBox, the driver loaded but then hung when I tried to access an ext2 filesystem. On a 32-bit Mac Mini, I got error messages when I tried to access an ext2 filesystem. As I write, the code was last updated in March of 2012. If you check the project and it's been updated more recently, it might be worth trying. Otherwise, I can't recommend this driver. I mention it here only in case it improves in the future.</li>
318
319 <li><b>Paragon's UFSD</b>&mdash;According to <a href="http://blog.paragon-software.com/?p=2951">this blog post,</a> Paragon Software has ported its <a href="http://www.paragon-software.com/technologies/ufsd.html">Universal File System Drivers (UFSD)</a> to EFI, providing "transparent access to NTFS, HFS+, ExFAT, and ExtFS" (sic). The entry doesn't provide any download links, and it's unclear if the product is (or will be) available for free or on a pay basis. I haven't tried these drivers, so I can't comment on their quality.</li>
320
321 </ul>
322
323 <p>The rEFIt, Clover, and VirtualBox drivers are related, and all of them
324 have fed into rEFInd's drivers. Specific versions can have their own
325 quirks, though. For instance, the Clover (and I suspect VirtualBox) drivers
326 don't return volume labels, which causes rEFInd to display loaders on those
327 volumes as being on a disk called <tt>Unknown</tt>. (I fixed that bug for
328 rEFInd's version, and it wasn't present in the original rEFIt drivers.)
329 Most of these drivers also suffer from speed problems on some computers.
330 This is worst with the ext2fs drivers under VirtualBox; on my main
331 computer, that combination takes 3 minutes to load a Linux kernel and
332 initial RAM disk file! Most real computers don't suffer nearly so badly,
333 but some can take an extra five seconds or so to boot a kernel. I've fixed
334 the speed problems in rEFInd's drivers as of version 0.7.0.</p>
335
336 <p>Driver availability could increase in the future. If you know of
337 additional EFI drivers, please <a href="mailto:rodsmith@rodsbooks.com">tell
338 me about them,</a> so I can share the information here. Likewise if you
339 know of a source for other EFI drivers&mdash;say, for a video card or disk
340 controller card.</p>
341
342 <p>Once you've obtained an EFI driver, you can install it in rEFInd just as you would install rEFInd's own drivers, as described earlier.</p>
343
344 <a name="notes">
345 <h2>Notes on Specific Drivers</h2>
346 </a>
347
348 <p>I've tested several of the drivers described on this page on a handful
349 of systems. The Pfisterer ext2fs driver (from any source) works on both
350 ext2fs and ext3fs, but not on ext4fs&mdash;but Agner's derivative ext4fs
351 driver handles ext4fs, so that's not a problem. The ReiserFS driver is
352 obviously useful only on ReiserFS partitions. (Reiser4 is not supported, as
353 far as I know.) The Btrfs driver is the newest of the Linux filesystem
354 drivers included with rEFInd, and so I've tested it the least, but it's
355 worked for me on several test systems. Given that ext2fs, ext3fs, and
356 ReiserFS are getting a bit on in age by Linux standards, you might do well
357 to use them on a separate Linux <tt>/boot</tt> partition; however, if
358 you're willing to use ext3fs, ext4fs, Btrfs, or ReiserFS on your root
359 (<tt>/</tt>) filesystem, you can use the EFI drivers to read your kernel
360 from it. Note that this assumes you use conventional partitions; to the
361 best of my knowledge, there's no EFI driver for Linux's Logical Volume
362 Manager (LVM) or Redundant Array of Independent Disks (RAID)
363 configurations, so the EFI can't access filesystems stored in these
364 ways.</p>
365
366 <p>As noted earlier, rEFInd's drivers prior to version 0.7.0, as well as related drivers from rEFIt, Clover, and VirtualBox, suffer from speed problems. These problems are mostly minor, adding a second or two to boot times; but on some computers, the speed problems can be dramatic, boosting kernel-load times up to as much as three minutes (under VirtualBox). If you run into excessive boot times with such a driver, try switching to the latest rEFInd driver instead. You might also try Pete Batard's efifs drivers.</p>
367
368 <p>Although ext2fs, ext3fs, ext4fs, and ReiserFS are all case-sensitive, these drivers treat them in a case-insensitive way. Symbolic links work; however, rEFInd 0.6.11 and later ignore symbolic links, since many distributions use them in a way that creates redundant or non-functional entries in the rEFInd menu. You should be able to use hard links if you want to use a single kernel file in multiple ways (say for two distributions).</p>
369
370 </ul>
371
372 <hr />
373
374 <p>copyright &copy; 2012&ndash;2015 by Roderick W. Smith</p>
375
376 <p>This document is licensed under the terms of the <a href="FDL-1.3.txt">GNU Free Documentation License (FDL), version 1.3.</a></p>
377
378 <p>If you have problems with or comments about this Web page, please e-mail me at <a href="mailto:rodsmith@rodsbooks.com">rodsmith@rodsbooks.com.</a> Thanks.</p>
379
380 <p><a href="index.html">Go to the main rEFInd page</a></p>
381
382 <p><a href="linux.html">Learn about how to adjust rEFInd's appearance</a></p>
383
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