Re: port-amd64/42597: LAPIC MSR address mask 4 bits short

[murray%river-styx.org@localhost]

The following reply was made to PR port-amd64/42597; it has been noted by GNATS.

From: murray%river-styx.org@localhost
To: gnats-bugs%NetBSD.org@localhost
Cc: david%l8s.co.uk@localhost
Subject: Re: port-amd64/42597: LAPIC MSR address mask 4 bits short
Date: Sun, 10 Jan 2010 12:03:56 +1100

 Hi David,
    Yeah, the MSR's are read using special instructions, specifically using
 the assembly routines rdmsr and wrmsr where hi 32 bits are in rdx and
 low 32 bits in rax. The Intel documentation doesn't mention any
 variations to this instruction for all 64 and IA-32 platform's, other
 than on models which don't have the instructions in the first place.
    I overlooked the i386 aspects of my suggested change and I see that it
 is not quite so straight forward. On standard i386 platform's i guess
 that the upper 4 bits past 32 are not relevant for addressing. When
 running, say PAE, where the address space is bigger might allow for
 such possible addresses of an APIC.
    A little more thought required here...
 Take care,
    murray armfield
 
 
 > The following reply was made to PR port-amd64/42597; it has been noted by
 > GNATS.
 >
 > From: David Laight <david%l8s.co.uk@localhost>
 > To: gnats-bugs%NetBSD.org@localhost
 > Cc: port-amd64-maintainer%netbsd.org@localhost, 
 > gnats-admin%netbsd.org@localhost,
 >      netbsd-bugs%netbsd.org@localhost
 > Subject: Re: port-amd64/42597: LAPIC MSR address mask 4 bits short
 > Date: Sat, 9 Jan 2010 11:33:49 +0000
 >
 >  On Sat, Jan 09, 2010 at 10:40:01AM +0000, murray%river-styx.org@localhost 
 > wrote:
 >  >  #      define  LAPIC_MSR_ENABLE        0x00000800      /* software
 > enable */
 >  > -#      define  LAPIC_MSR_ADDR          0xfffff000      /* physical
 > address */
 >  > +#      define  LAPIC_MSR_ADDR          0xffffff000     /* physical
 > address */
 >
 >  That value is out of range for an integer constant.
 >  I'd have to read the docs, but aren't the MSRs accessed using special
 >  instructions - do that have > 32 bits physical address, especially on
 > i386?
 >
 >      David
 >
 >  --
 >  David Laight: david%l8s.co.uk@localhost
 >
 >