Subject: FPU interrupt handler

From: William Lee Irwin III <[email-masked]>
Date: Sun, 25 Nov 2001 00:23:52 -0800

EXPORT(dec_intr_fpu)
dec_intr_fpu:   PANIC("Unimplemented FPU interrupt handler")

I've not encountered this quite yet, but I have an R3K-based
DecStation up and running, and if I understand this properly,
R3K delivers FPU exceptions as interrupts. It looks like
this could take the machine down.

Maciej, I was asked to notify you specifically, but this is
my only known point of contact. If you could look into this,
I would be much obliged.

Thanks,
Bill

---

From: "Maciej W. Rozycki" <[email-masked]>
Date: Mon, 26 Nov 2001 12:57:23 +0100 (MET)

> this could take the machine down.

 Nope, R3k DECstations used to use the FPU emulator unconditionally. :-(
This would have never got triggered.  An FPU interrupt-to-exception glue
was non-existent.

> my only known point of contact. If you could look into this,

 No need to do anything -- I happened to work on the FPU a bit recently
and I sent a patch here on Friday that adds the glue, enables the FPU and
rips the broken code off.  Ralf has already applied the patch. 

 I would *really* appreciate any feedback on DECstation patches I'm
sending here -- for quite some time I have a feeling I'm the last one to
run Linux on a DECstation... :-(

  Maciej

-- 
+  Maciej W. Rozycki, Technical University of Gdansk, Poland   +
+--------------------------------------------------------------+
+        e-mail: [email-masked], PGP key available        +

---

From: "Houten K.H.C. van (Karel)" <[email-masked]>
Date: Mon, 26 Nov 2001 13:19:56 +0100

Hi Maciej

> run Linux on a DECstation... :-(

I would love to do more work on my DECstation, but I had some disk
problems recently, and I don't seem te get any newer kernels
then 2.4.0-test9 running after a native compile by the toolchain
provided by H.J. Lu.

Some kernels don't start-up, others hang just before forking init,
and all have problems with my serial console.

When I get a recent kernel running again, I would love to update my
DECStation Linux Website with newer instructions and a new root FS.

Regards,

-- 
Karel van Houten

----------------------------------------------------------
The box said "Requires Windows 95 or better."
I can't understand why it won't work on my Linux computer. 
----------------------------------------------------------

---

From: Ralf Baechle <[email-masked]>
Date: Tue, 27 Nov 2001 00:24:05 +1100

> run Linux on a DECstation... :-(

Certainly not, on the recent Linux porter meating it was probably the
most used type of non-x86 machine.  So rather blame general passivity
of man kind ...

  Ralf

---

From: "Maciej W. Rozycki" <[email-masked]>
Date: Mon, 26 Nov 2001 14:50:13 +0100 (MET)

Hi Karel,

> then 2.4.0-test9 running after a native compile by the toolchain

 Hmm, for R3k gcc 2.95.3 + binutils 2.11.2 as available at my site seem to
be rock solid.

 For R4k you need binutils 2.11.92, as there is a problem with dla/la
expansion in the Ulf's patch for .mips3+.  That actually can be fixed in
2.11.2 easily but I was going to switch to 2.11.92 anyway, as it has more
MIPS/Linux support integrated and 2.12 is supposedly soon to be released.
Unfortunately 2.11.92 is not as stable as 2.11.2 due to generic ELF code
problems, but I'm trying to track changes and spot a more stable snapshot.

> and all have problems with my serial console.

 Well, I'm very happy with a /240 running a 2.4.14 snapshot dated
20011123.  For a /260 I need a small, but critical bugfix I'm sending to
the list right now.  I wonder how was it possible for the bug to remain
uncovered for so long as it's absolutely lethal and often triggered (I've
only got my /260 recently and it wasn't even running a few minutes
continuously before the fix). 

 I can't comment other models.

> DECStation Linux Website with newer instructions and a new root FS.

 I may upload binaries of my kernels to my site if they are to be useful
-- they are fully monolithic (but with kmod support) due to historical
reasons.  Only IPv6 is modular due to its unstability -- it freezes the
system immediately on my /240 and splashes a bunch of suspicious messages
on my /260 (weird, but no time to debug).  They only support /240 and /260
due to CONFIG_CPU_HAS_WB unset.

  Maciej

---

From: "Houten K.H.C. van (Karel)" <[email-masked]>
Date: Mon, 26 Nov 2001 15:07:54 +0100

Hi Maciej,

> problems, but I'm trying to track changes and spot a more stable snapshot.

I'm using the RedHat 7.1 packages from oss:
binutils-2.11.92.0.10-1.mips.rpm
gcc-2.96-99.1.mips.rpm

> continuously before the fix). 
My 'main' mips box at home is a /260. I sometimes test things out on
a /240, but I don't have access to other boxes.
 
> due to CONFIG_CPU_HAS_WB unset.

Yes please. I hope to get a new disk this week, so I can build a
stable development server...

Thanks a lot,

-- 
Karel van Houten

---

From: William Lee Irwin III <[email-masked]>
Date: Mon, 26 Nov 2001 06:48:53 -0800

> This would have never got triggered.  An FPU interrupt-to-exception glue

Okay, that is at least some relief.

> rips the broken code off.  Ralf has already applied the patch. 

Excellent! I'll apply it as well.

> run Linux on a DECstation... :-(

Well, I'm a more than willing tester, and perhaps I can even bring some
code to the table in my spare time at some point for the drivers my
system needs help with.

Cheers,
Bill

---

From: "Maciej W. Rozycki" <[email-masked]>
Date: Mon, 26 Nov 2001 17:10:53 +0100 (MET)

> most used type of non-x86 machine.  So rather blame general passivity

 Well, but what can I think when even fatal core errors remain
unnoticed?...  The int-handler.S was one and the file wasn't changed for a
very long time, i.e. since I fixed another fatal error there...  And both
looked like they were present from the day one...

---

From: "Maciej W. Rozycki" <[email-masked]>
Date: Mon, 26 Nov 2001 17:20:26 +0100 (MET)

Hi Karel,

> binutils-2.11.92.0.10-1.mips.rpm

 Can't comment on these.  I feel a bit uneasy about gcc 2.96, possibly due
to the way it was incarnated.  I'll probably switch directly to 3.x when
it's proved stable enough not to distract me from primary tasks.  I don't
know how much binutils 2.11.92.0.10 differ from the mainline.

> >  I may upload binaries of my kernels to my site if they are to be useful
[...]
> stable development server...

 OK -- I should have them by tomorrow.

  Maciej

---

From: "Maciej W. Rozycki" <[email-masked]>
Date: Mon, 26 Nov 2001 17:20:26 +0100 (MET)

Hi Karel,

[...]

  Maciej

---

From: Ralf Baechle <[email-masked]>
Date: Tue, 27 Nov 2001 12:17:24 +1100

> looked like they were present from the day one...

In that case if nobody complains those nobodies all had their fair chance :-)

  Ralf

---

From: "Maciej W. Rozycki" <[email-masked]>
Date: Tue, 27 Nov 2001 18:35:02 +0100 (MET)

> stable development server...

 The kernels are now available at
'ftp://ftp.ds2.pg.gda.pl/pub/macro/linux/'.

---

From: "Maciej W. Rozycki" <[email-masked]>
Date: Tue, 27 Nov 2001 18:35:02 +0100 (MET)