Re: PROBLEM:Illegal instruction when mount nfs file systems using cyr ixIII

Re: PROBLEM:Illegal instruction when mount nfs file systems using cyr ixIII

[Mikael Pettersson]

On Wed, 27 Jun 2001 17:42:01 +0800, Frank Zhu wrote:

>I use a PIII machine as the server and cyrixIII machine as the client.The
>kernel is 2.4.5.The distribute is red hat 7.1
>when i mount the nfs file system at the client it failed.The core file is
>created.using the gdb it report  :
>Program terminated with signal 4(SIGILL),Illegal instruction
>#0  0x40003e28 in ??()
>
>If i change the cpu (CyrixIII) to PIII all is ok.

You don't say exactly where the failure occurs, but I suspect
that you're feeding i686-class machine code to your VIA Cyrix III.

The problem is that VIA Cyrix III announces itself (via CPUID)
as a "family 6" processor, i.e. i686 compatible. This is not
completely accurate, since it doesn't implement the conditional
move instruction. [Yeah, I know there's a CPUID feature flag for
CMOV. I also know gcc doesn't check it, and I suspect glibc
doesn't either.]

To make the machine work you'll have to ensure that the kernel,
user-space libraries and programs, and NFS-imported programs
all are compiled for a lesser CPU than i686.

/Mikael

Re: PROBLEM:Illegal instruction when mount nfs file systems using cyr ixIII

[Alan Cox]

> The problem is that VIA Cyrix III announces itself (via CPUID)
> as a "family 6" processor, i.e. i686 compatible. This is not
> completely accurate, since it doesn't implement the conditional
> move instruction. [Yeah, I know there's a CPUID feature flag for

Intel specifically state that you cannot use CMOV without checking
for it. Its actually a gcc/binutils tool bug. The CPU is right.

> To make the machine work you'll have to ensure that the kernel,
> user-space libraries and programs, and NFS-imported programs
> all are compiled for a lesser CPU than i686.

For RH 

	rpm -qa |grep ".i686*"

and update the packages listed with their i586/i386 ones. 

Alan

Re: PROBLEM:Illegal instruction when mount nfs file systems using cyr ixIII

[Bernd Schmidt]

On Wed, 27 Jun 2001, Alan Cox wrote:

> > The problem is that VIA Cyrix III announces itself (via CPUID)
> > as a "family 6" processor, i.e. i686 compatible. This is not
> > completely accurate, since it doesn't implement the conditional
> > move instruction. [Yeah, I know there's a CPUID feature flag for
>
> Intel specifically state that you cannot use CMOV without checking
> for it. Its actually a gcc/binutils tool bug. The CPU is right.

How is that a gcc bug?  You tell the compiler to generate cmov, you run
it on a CPU that doesn't have it, you get what you deserve.  There's
really nothing the tools can do about that.


Bernd

Re: PROBLEM:Illegal instruction when mount nfs file systems using

[Alan Cox]

> > Intel specifically state that you cannot use CMOV without checking
> > for it. Its actually a gcc/binutils tool bug. The CPU is right.
> 
> How is that a gcc bug?  You tell the compiler to generate cmov, you run
> it on a CPU that doesn't have it, you get what you deserve.  There's
> really nothing the tools can do about that.

I tell gcc to buld for the 'i686' architecture definition. It in fact builds
for the i686 architecture assuming an optional feature. Intel's own PPro doc
is quite explicit that cmov could go away again in future chips.

So cmov should not have been in the 686 machine definition.

Alan

PROBLEM:Illegal instruction when mount nfs file systems using cyr ixIII

[Frank Zhu (Shanghai)]

hi:
I use a PIII machine as the server and cyrixIII machine as the client.The
kernel is 2.4.5.The distribute is red hat 7.1
when i mount the nfs file system at the client it failed.The core file is
created.using the gdb it report  :
Program terminated with signal 4(SIGILL),Illegal instruction
#0  0x40003e28 in ??()

If i change the cpu (CyrixIII) to PIII all is ok.

help

frank