From: YunQiang Su <syq@debian.org>
Date: Mon, 16 Nov 2020 01:11:00 +0000 (+0800)
Subject: Use RELAXED ieee754 mode for Loongson-3 as 3A 4000 is 2008-only
X-Git-Tag: archive/raspbian/5.18.16-1+rpi1^2~88
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=af8992216721ea07494af300ad590fef4d468b2d;p=linux.git

Use RELAXED ieee754 mode for Loongson-3 as 3A 4000 is 2008-only

Forwarded: not-needed

There are 2 mode of value of IEEE NaN hardcoded by CPU.
Currently, our mipsel/mips64el port is in so-called lagacy mode.
Loongson 3A 4000 is set as the so-called 2008 mode.

To make Debian workable on Loongson 3A 4000, we need set the kerenl in
RELAXED mode.

https://web.archive.org/web/20180830093617/https://dmz-portal.mips.com/wiki/MIPS_ABI_-_NaN_Interlinking


Gbp-Pq: Topic debian
Gbp-Pq: Name mips-ieee754-relaxed.patch
---

diff --git a/arch/mips/kernel/fpu-probe.c b/arch/mips/kernel/fpu-probe.c
index e689d6a8323..667226f94c8 100644
--- a/arch/mips/kernel/fpu-probe.c
+++ b/arch/mips/kernel/fpu-probe.c
@@ -144,7 +144,12 @@ static void cpu_set_fpu_2008(struct cpuinfo_mips *c)
  * IEEE 754 conformance mode to use.  Affects the NaN encoding and the
  * ABS.fmt/NEG.fmt execution mode.
  */
-static enum { STRICT, LEGACY, STD2008, RELAXED } ieee754 = STRICT;
+enum ieee754_mode { STRICT, LEGACY, STD2008, RELAXED };
+#ifdef CONFIG_CPU_LOONGSON64
+static enum ieee754_mode ieee754 = RELAXED;
+#else
+static enum ieee754_mode ieee754 = STRICT;
+#endif
 
 /*
  * Set the IEEE 754 NaN encodings and the ABS.fmt/NEG.fmt execution modes