Re: Bug#834844: release-notes: document that mips* arches now require a R2 CPU

James Cowgill <[email protected]> Thu, 25 Aug 2016 14:42:15 +0100

Newsgroups	gmane.linux.debian.ports.mips
Message-ID	<[email protected]>

Hi,

On 25/08/16 14:17, Ed Swierk wrote:
> This mips32r2 requirement also appears to exclude Cavium Octeon:
> 
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/mips/include/asm/mach-cavium-octeon/cpu-feature-overrides.h#n50
> 
> If that's accurate, it would be worth mentioning in the release notes as well.

*sigh* Cavium Octeon machines do support R2 (mips32r2 is a subset of
mips64r2) but for some reason unknown to me, don't actually expose this.
I've adjusted the check to look for mips64r2 as well and attached a new
patch.

Thanks,
James

> On Thu, Aug 25, 2016 at 4:10 AM, James Cowgill <[email protected]> wrote:
>> Control: tags -1 patch
>>
>> On 19/08/16 22:42, Aurelien Jarno wrote:
>>> This is something to be expected as the mips and mipsel port now
>>> defaults to using R2 instructions set. This means the Loongson 2
>>> CPUs are not supported anymore (this includes the Yeeloong machine).
>>>
>>> I have asked many times to document this changes in the release notes,
>>> but this hasn't been done yet. I am therefore reassigning the bug there,
>>> Cc:ing debian-mips so that somone can take care of that.
>>
>> How about the attached patch? It's loosely based on the i686 notes just
>> above.
>>
>> I also changed the "human readable" mips architecture names since all
>> the other arches seem to have them.
>>
>> James

mips-r2-relnotes-v2.diff (text/x-patch, 2 KB)

Index: en/issues.dbk
===================================================================
--- en/issues.dbk	(revision 11283)
+++ en/issues.dbk	(working copy)
@@ -118,6 +118,31 @@
       to i686 for the Debian i386 architecture</ulink>.
     </para>
   </section>
+  <section id="mips-requires-r2-processor" arch="mips;mipsel">
+    <!-- Jessie to Stretch -->
+    <title>32-bit MIPS now requires an R2 processor</title>
+    <para>
+      The 32-bit MIPS support (both big and little endian) now requires a
+      processor supporting MIPS32 Release 2 of the MIPS instruction set.
+      Notably the Loongson-2E/2F and systems based on them (including the
+      Yeeloong laptop) are no longer supported.
+    </para>
+    <para>
+      The following shell script can be used to indicate if your machine
+      supports R2 (assuming only one type of processor is present). Note that
+      Loongson-3 processors are supported even though they only claim to
+      support MIPS32 Release 1.
+    </para>
+    <screen>
+if grep -E -q '^isa.*\bmips(32|64)r2\b' /proc/cpuinfo; then
+	echo "OK (R2 supported)"
+elif grep -q '^cpu model.*\bICT Loongson-3\b' /proc/cpuinfo; then
+	echo "OK (Loongson 3)"
+else
+	echo "NOT OK: R2 not supported"
+fi
+</screen>
+  </section>
 </section>
 
 <section id="limited-security-support">
Index: release-notes.ent
===================================================================
--- release-notes.ent	(revision 11283)
+++ release-notes.ent	(working copy)
@@ -87,8 +87,8 @@
 		  --><phrase arch='armel'>ARM EABI</phrase><!--
 		  --><phrase arch='armhf'>ARMv7 (EABI hard-float ABI)</phrase><!--
 		  --><phrase arch='i386'>32-bit PC</phrase><!--
-		  --><phrase arch='mips'>Mips</phrase><!--
-		  --><phrase arch='mipsel'>Mipsel</phrase><!--
+		  --><phrase arch='mips'>32-bit MIPS (big endian)</phrase><!--
+		  --><phrase arch='mipsel'>32-bit MIPS (little endian)</phrase><!--
 		  --><phrase arch='powerpc'>PowerPC</phrase><!--
 		  --><phrase arch='ppc64el'>64-bit little-endian PowerPC</phrase><!--
 		  --><phrase arch='s390'>S/390</phrase><!--

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