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From: Joshua Kinard <kumba@gentoo.org>
To: Linux MIPS List <linux-mips@linux-mips.org>
Cc: Ralf Baechle <ralf@linux-mips.org>,
	"Maciej W. Rozycki" <macro@linux-mips.org>
Subject: IP27: R14000: Unexpected General Exception in cpu_set_fpu_fcsr_mask()
Date: Sat, 30 May 2015 01:00:09 -0400	[thread overview]
Message-ID: <556943D9.7020502@gentoo.org> (raw)

Booting a recent kernel on an IP27 system with R14K nodeboards causes the PROM
to bail:

ttyS0:
Command Monitor.  Type "exit" to return to the menu.
>> bootp(): console=ttyS0,9600 root=/dev/md0
Setting $netaddr to 192.168.1.x (from server )
Obtaining  from server
9036672+495920 entry: 0xa800000000689300

MMC:
2A 000: *** General Exception on node 0
2A 000: *** EPC: 0xa800000000022178 (0xa800000000022178)
2A 000: *** Press ENTER to continue.
2A 000: POD MSC Unc> why
2A 000:  EPC    : 0xa800000000022178 (0xa800000000022178)
2A 000:  ERREPC : 0xffffffffbfc00ee0 (0xc00000001fc00ee0)
2A 000:  CACERR : 0x00000000d6d7ff21
2A 000:  Status : 0x0000000024407c80
2A 000:  BadVA  : 0x0000000000000000 (0x0)
2A 000:  RA     : 0xa8000000008771cc (0xa8000000008771cc)
2A 000:  SP     : 0xa80000000081be00
2A 000:  A0     : 0x00000000000051a1
2A 000:  Cause  : 0x000000000000c03c (INT:87------ <Float Pt. Exc>)
2A 000:  Reason : 242 (Unexpected General Exception.)
2A 000:  POD mode was called from: 0xc00000001fc027ec (0xc00000001fc027ec)
2A 000: POD MSC Unc>

Address 0xa800000022178 centers around line 85 in 4.1.0-rc4's
arch/mips/cpu-probe.c:

85:         write_32bit_cp1_register(CP1_STATUS, fcsr0);
    a80000000002216c:       3c020003        lui     v0,0x3
    a800000000022170:       3445ffff        ori     a1,v0,0xffff
    a800000000022174:       00851024        and     v0,a0,a1
--> a800000000022178:       44c2f800        ctc1    v0,$31
    a80000000002217c:       00000000        nop

Looks like cpu_set_fpu_fcsr_mask() was added in April sometime:

http://git.linux-mips.org/cgit/ralf/linux.git/commit/arch/mips/kernel/cpu-probe.c?id=9b26616c8d9dae53fbac7f7cb2c6dd1308102976

Not sure what else can be gleaned.  Seems this version of the R14K (v1.4)
doesn't like that FCSR mask.  Don't recall the Octane complaining about this,
but I'll try to double-check tomorrow.  It's got a newer rev of R14K silicon.
Might be an errata.

--J

             reply	other threads:[~2015-05-30  5:00 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-05-30  5:00 Joshua Kinard [this message]
2015-06-01  0:09 ` IP27: R14000: Unexpected General Exception in cpu_set_fpu_fcsr_mask() Maciej W. Rozycki
2015-06-01  2:57   ` Joshua Kinard
2015-06-01 11:27     ` Maciej W. Rozycki
2015-06-01 20:16       ` Ralf Baechle
2015-06-02  4:56       ` Joshua Kinard
2015-06-02  6:51         ` Ralf Baechle
2015-06-02 11:42           ` Maciej W. Rozycki
2015-06-02 11:32         ` Maciej W. Rozycki
2015-06-02 18:56           ` Joshua Kinard
2015-06-02 18:56             ` Joshua Kinard

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