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Re: Can't build a CONFIG_CPU_NEVADA kernel

To: "Kevin D. Kissell" <kevink@mips.com>
Subject: Re: Can't build a CONFIG_CPU_NEVADA kernel
From: Pete Popov <ppopov@mvista.com>
Date: Wed, 14 Mar 2001 17:50:06 -0800
Cc: linux-mips@oss.sgi.com
Organization: Monta Vista Software
References: <20010314084633.A25674@nevyn.them.org> <20010314195919.A1911@bacchus.dhis.org> <20010314140529.A29525@nevyn.them.org> <20010314202058.B1911@bacchus.dhis.org> <00fc01c0acd3$c881ca80$0deca8c0@Ulysses> <011001c0acd8$c27a9220$0deca8c0@Ulysses>
Sender: owner-linux-mips@oss.sgi.com
"Kevin D. Kissell" wrote:
> 
> > "Correct" usage would be to enable those three instructions
> > with a "-mcpu=nevada", or better still, "-mcpu=r5200" (for
> > consistency), and to enable the rest of the MIPS IV ISA
> > with "-mips4" instead of the archaic r8000 hack.
> 
> I should add "Correct", but not useful for 32-bit
> kernels.  "-mips32", once that percolates through
> the gcc food chain, would be *almost* perfect
> for 32-bit Nevada kernels.  I say almost, because
> while MIPS32 is 32-bit MIPS IV plus MADD, it also
> has a handfull of instructions that are not supported
> by the R52xx, of which it is wildly improbable but
> theoretically possible that the multiply-subtracts
> might somehow get emitted in compiled application
> code. It should work just fine for kernel purposes, though.
> 
> Meanwhile, try piping objdump of a "-mmad" kernel
> through "grep -i mad".  I'd be stunned if a single MADD
> turned up.  If it gains nothing, but breaks builds, then
> for heaven's sake banish -mmad from the kernel
> makefiles!

I managed to compile a 2.4.2 kernel with our bleeding edge toolchain. I
had to get rid of the -mmad from the Makefile though. The kernel boots
and runs and I ran Bonnie over NFS as well as on an IDE hard disk. I
tried some other tests as well, and they all passed.  

Without the -mmad flag, I see the following mad instructions below. No
"madd" though, just madd.s, madd16, mad, etc. So, can we get rid of this
flag in the Makefile?

Pete

0000000080132690 <sys_madvise>:
    801326dc:   1080fffc        beqz    $a0,801326d0 <sys_madvise+40>
    801326e4:   04810004        bgez    $a0,801326f8 <sys_madvise+68>
    801326f8:   5440002e        bnezl   $v0,801327b4 <sys_madvise+124>
    80132714:   54400027        bnezl   $v0,801327b4 <sys_madvise+124>
    8013271c:   12510024        beq     $s2,$s1,801327b0
<sys_madvise+120>
    80132734:   1200001e        beqz    $s0,801327b0 <sys_madvise+120>
    80132744:   10400003        beqz    $v0,80132754 <sys_madvise+c4>
    80132758:   1440000c        bnez    $v0,8013278c <sys_madvise+fc>
    80132764:   10400007        beqz    $v0,80132784 <sys_madvise+f4>
    80132770:   0c04c988        jal     80132620 <madvise_vma>
    8013277c:   5660000d        bnezl   $s3,801327b4 <sys_madvise+124>
    80132784:   0804c9ec        j       801327b0 <sys_madvise+120>
    80132790:   0c04c988        jal     80132620 <madvise_vma>
    8013279c:   56600005        bnezl   $s3,801327b4 <sys_madvise+124>
    801327a8:   0804c9cd        j       80132734 <sys_madvise+a4>
    801327c8:   1080fffc        beqz    $a0,801327bc <sys_madvise+12c>
    801327d0:   1c800004        bgtz    $a0,801327e4 <sys_madvise+154>
    80250590:   4d4d2030        nmadd.s $f0,$f10,$f4,$f13
    80250a84:   4f4e2820        madd.s  $f0,$f26,$f5,$f14
    802517bc:   00000029        dmadd16 $zero,$zero
    80253c94:   00000029        dmadd16 $zero,$zero
    802555a4:   00000029        dmadd16 $zero,$zero
    80256178:   00000029        dmadd16 $zero,$zero
    80259804:   4d445b20        madd.s  $f12,$f10,$f11,$f4
    80259810:   4d445b20        madd.s  $f12,$f10,$f11,$f4
    8025981c:   4d445b20        madd.s  $f12,$f10,$f11,$f4
    8025aa34:   00000029        dmadd16 $zero,$zero
    8025bbf0:   4c257830        nmadd.s $f0,$f1,$f15,$f5
    802618a8:   4f2f4920        madd.s  $f4,$f25,$f9,$f15
    80262018:   4e203a70        nmadd.s $f9,$f17,$f7,$f0
    802625c4:   4c554e20        madd.s  $f24,$f2,$f9,$f21
    80262700:   4c554e20        madd.s  $f24,$f2,$f9,$f21
    80264d5c:   4c545220        madd.s  $f8,$f2,$f10,$f20
    80264d64:   00000029        dmadd16 $zero,$zero
    80265148:   4e203d21        madd.d  $f20,$f17,$f7,$f0
    80265194:   4e203d21        madd.d  $f20,$f17,$f7,$f0
    8026534c:   00000029        dmadd16 $zero,$zero
    80265b50:   4f495020        madd.s  $f0,$f26,$f10,$f9
    80265f70:   4c554e20        madd.s  $f24,$f2,$f9,$f21
    80266294:   4e554c20        madd.s  $f16,$f18,$f9,$f21
    802670bc:   4c4c4120        madd.s  $f4,$f2,$f8,$f12
    80267690:   4d207361        madd.d  $f13,$f9,$f14,$f0
    80267f5c:   00000029        dmadd16 $zero,$zero
    80268314:   00000029        dmadd16 $zero,$zero
    80268abc:   00000029        dmadd16 $zero,$zero
    80269cd4:   4d435020        madd.s  $f0,$f10,$f10,$f3
    8026a504:   00000029        dmadd16 $zero,$zero
    8026df88:   4c4c5020        madd.s  $f0,$f2,$f10,$f12
    8026e01c:   4c502070        nmadd.s $f1,$f2,$f4,$f16
    8026f6bc:   4c622020        madd.s  $f0,$f3,$f4,$f2
    8026f71c:   4e622020        madd.s  $f0,$f19,$f4,$f2
    8026f944:   4c622020        madd.s  $f0,$f3,$f4,$f2
    8026f9f0:   4d772020        madd.s  $f0,$f11,$f4,$f23
    802702f8:   4d203231        nmadd.d $f8,$f9,$f6,$f0
    80273830:   00000029        dmadd16 $zero,$zero
    80276a24:   4f6d7361        madd.d  $f13,$f27,$f14,$f13
    80277498:   4e203d21        madd.d  $f20,$f17,$f7,$f0
    80279c10:   4d202020        madd.s  $f0,$f9,$f4,$f0
    80279ea4:   4d434920        madd.s  $f4,$f10,$f9,$f3
    8027c588:   4f494520        madd.s  $f20,$f26,$f8,$f9
    80280048:   4d642520        madd.s  $f20,$f11,$f4,$f4
    802802c8:   4d4f5220        madd.s  $f8,$f10,$f10,$f15
    802a0e00:   4e414d20        madd.s  $f20,$f18,$f9,$f1
    802a2988:   4c4f5720        madd.s  $f28,$f2,$f10,$f15
    802a2a30:   00000029        dmadd16 $zero,$zero
    802a2c14:   4f2f4920        madd.s  $f4,$f25,$f9,$f15
    802a336c:   4f2f4920        madd.s  $f4,$f25,$f9,$f15
    802a39e4:   00000029        dmadd16 $zero,$zero
    802a3a00:   00000029        dmadd16 $zero,$zero
    802a3a1c:   00000029        dmadd16 $zero,$zero
    802a3a70:   00000029        dmadd16 $zero,$zero
    802a3ac8:   00000029        dmadd16 $zero,$zero
    802a3ad0:   4d353531        nmadd.d $f20,$f9,$f6,$f21
    802a3b3c:   00000029        dmadd16 $zero,$zero
    802a427c:   4f2f4920        madd.s  $f4,$f25,$f9,$f15
    802a50bc:   4d4f4320        madd.s  $f12,$f10,$f8,$f15
    802a5504:   4e414c20        madd.s  $f16,$f18,$f9,$f1
    802a57ec:   4c2e6920        madd.s  $f4,$f1,$f13,$f14
    802a5f18:   4f2f4920        madd.s  $f4,$f25,$f9,$f15
    802a6378:   4d544120        madd.s  $f4,$f10,$f8,$f20
    802a63b4:   4d207161        madd.d  $f5,$f9,$f14,$f0
    802a6d5c:   00000029        dmadd16 $zero,$zero
    802a6ea8:   4f2f4920        madd.s  $f4,$f25,$f9,$f15
    802a6ebc:   4f2f4920        madd.s  $f4,$f25,$f9,$f15
    802a73c0:   4e414c20        madd.s  $f16,$f18,$f9,$f1
    802a74cc:   4e414c20        madd.s  $f16,$f18,$f9,$f1
    802a75a0:   4f505420        madd.s  $f16,$f26,$f10,$f16
    802a7994:   4d502031        nmadd.d $f0,$f10,$f4,$f16
    802a7ac0:   4e414c20        madd.s  $f16,$f18,$f9,$f1
    802a7b54:   4e206870        nmadd.s $f1,$f17,$f13,$f0
    802a7e8c:   4d502820        madd.s  $f0,$f10,$f5,$f16
    802a7f84:   4e5b2061        madd.d  $f1,$f18,$f4,$f27
    802a7f90:   4e5b2061        madd.d  $f1,$f18,$f4,$f27
    802a7f9c:   4e5b2061        madd.d  $f1,$f18,$f4,$f27
    802a7fa8:   4e5b2061        madd.d  $f1,$f18,$f4,$f27
    802a8068:   00000029        dmadd16 $zero,$zero
    802a8290:   4d5b2030        nmadd.s $f0,$f10,$f4,$f27
    802a8c94:   4f525020        madd.s  $f0,$f26,$f10,$f18
    802a9088:   4e207370        nmadd.s $f13,$f17,$f14,$f0
    802a94ec:   4d544120        madd.s  $f4,$f10,$f8,$f20
    802a962c:   4d544120        madd.s  $f4,$f10,$f8,$f20
    802a9c10:   00000029        dmadd16 $zero,$zero
    802a9d64:   00000029        dmadd16 $zero,$zero
    802a9d80:   00000029        dmadd16 $zero,$zero
    802a9e2c:   00000029        dmadd16 $zero,$zero
    802ab81c:   00000029        dmadd16 $zero,$zero
    802ac17c:   00000029        dmadd16 $zero,$zero
    802ac65c:   4d207861        madd.d  $f1,$f9,$f15,$f0
    802ac740:   4d207861        madd.d  $f1,$f9,$f15,$f0
    802ac79c:   4c525320        madd.s  $f12,$f2,$f10,$f18
    802ad3e4:   4e206c61        madd.d  $f17,$f17,$f13,$f0
    802ad954:   4d202d20        madd.s  $f20,$f9,$f5,$f0
    802ae994:   4f2f4920        madd.s  $f4,$f25,$f9,$f15
    802af200:   4e415720        madd.s  $f28,$f18,$f10,$f1
    802b10cc:   4e414320        madd.s  $f12,$f18,$f8,$f1
    802b167c:   4e454420        madd.s  $f16,$f18,$f8,$f5
    802b1690:   4c554d20        madd.s  $f20,$f2,$f9,$f21
    802b1d88:   4d4f4320        madd.s  $f12,$f10,$f8,$f15
    802b1df0:   00000029        dmadd16 $zero,$zero
    802b2428:   00000029        dmadd16 $zero,$zero
    802b2458:   4d206e61        madd.d  $f25,$f9,$f13,$f0
    802b30e0:   00000029        dmadd16 $zero,$zero
    802b3140:   00000029        dmadd16 $zero,$zero
    802b3c68:   00000029        dmadd16 $zero,$zero
    802b3ff8:   4f525020        madd.s  $f0,$f26,$f10,$f18
    802b4010:   4f525020        madd.s  $f0,$f26,$f10,$f18
    802b4120:   4d472030        nmadd.s $f0,$f10,$f4,$f7
    802b453c:   4f2f4920        madd.s  $f4,$f25,$f9,$f15
    802b5d80:   00000029        dmadd16 $zero,$zero
    802b6e38:   00000028        madd16  $zero,$zero
    802b6e40:   00000029        dmadd16 $zero,$zero
    802b7350:   00000028        madd16  $zero,$zero
    802b80a8:   00000028        madd16  $zero,$zero
    802b80b0:   00000029        dmadd16 $zero,$zero
    802b81d8:   00000028        madd16  $zero,$zero
    802b81e0:   00000029        dmadd16 $zero,$zero
    802bdda4:   00000028        madd16  $zero,$zero
    802bddd8:   00000028        madd16  $zero,$zero
    802bde7c:   00000029        dmadd16 $zero,$zero
    802bdeac:   00000028        madd16  $zero,$zero
    802bdeb8:   00000028        madd16  $zero,$zero
    802bdf14:   00000028        madd16  $zero,$zero
    802be6d8:   00000028        madd16  $zero,$zero
    802be764:   00000028        madd16  $zero,$zero
    802c0578:   70000000        mad     $zero,$zero
    802c07f4:   72070000        mad     $s0,$a3
    802c1490:   00000028        madd16  $zero,$zero
    802c957c:   00000029        dmadd16 $zero,$zero
    802c96b0:   00000028        madd16  $zero,$zero
    802ccdcc:   00000028        madd16  $zero,$zero
    802cddb0:   00290028        madd16  $at,$t1
    802cdfb0:   00290028        madd16  $at,$t1
    802ce1b0:   00290028        madd16  $at,$t1
    802ce6b8:   00290028        madd16  $at,$t1
    802d4150:   4e534331        nmadd.d $f12,$f18,$f8,$f19
    802d667c:   00000028        madd16  $zero,$zero
    802d7614:   00290028        madd16  $at,$t1
    802d9770:   00000028        madd16  $zero,$zero
    802d9820:   00000029        dmadd16 $zero,$zero

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