Re: kern/39114: sys/arch/x86/x86/patch.c needs a minor #ifdef for PARALLELS (VT extensions problem)

[Jason Thorpe <thorpej%shagadelic.org@localhost>]

The following reply was made to PR kern/39114; it has been noted by GNATS.

From: Jason Thorpe <thorpej%shagadelic.org@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: kern-bug-people%netbsd.org@localhost,
 gnats-admin%netbsd.org@localhost,
 netbsd-bugs%netbsd.org@localhost,
 ggm%pobox.com@localhost
Subject: Re: kern/39114: sys/arch/x86/x86/patch.c needs a minor #ifdef for 
PARALLELS (VT extensions problem)
Date: Tue, 8 Jul 2008 07:45:12 -0700

 On Jul 8, 2008, at 3:40 AM, Jared D. McNeill wrote:
 
 > The following reply was made to PR kern/39114; it has been noted by  
 > GNATS.
 >
 > From: "Jared D. McNeill" <jmcneill%invisible.ca@localhost>
 > To: gnats-bugs%NetBSD.org@localhost
 > Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
 > netbsd-bugs%netbsd.org@localhost
 > Subject: Re: kern/39114: sys/arch/x86/x86/patch.c needs a minor  
 > #ifdef for
 > PARALLELS (VT extensions problem)
 > Date: Tue, 08 Jul 2008 02:35:44 -0400
 >
 > ggm%pobox.com@localhost wrote:
 >>> Number:         39114
 >>> Category:       kern
 >>> Synopsis:       sys/arch/x86/x86/patch.c needs a minor #ifdef for  
 >>> PARALLELS (VT extensions problem)
 >>> Confidential:   no
 >>> Severity:       non-critical
 >>> Priority:       low
 >>> Responsible:    kern-bug-people
 >>> State:          open
 >>> Class:          sw-bug
 >>> Submitter-Id:   net
 >>> Arrival-Date:   Tue Jul 08 02:05:00 +0000 2008
 >>> Originator:     George Michaelson
 >>> Release:        current
 >>> Organization:
 >>> Environment:
 >> NetBSD snoid 4.99.69 NetBSD 4.99.69 (GENERIC) #3: Mon Jul  7  
 >> 20:34:51 EST 2008  ggm@snoid:/usr/obj/sys/arch/i386/compile/GENERIC  
 >> i386
 >>> Description:
 >> Parallels on Mac has support for 'VT extensions' but when they hit  
 >> a NetBSD current kernel, some code in patch.c causes a hang during  
 >> boot.
 >>
 >> You can disable the VT extensions, but thats a PITA. There is an  
 >> existing #if !defined(GPROF) on the code which causes the problem,  
 >> but having to enable GPROF to get a working kernel also has  
 >> downsides.
 >>
 >> If this patch is acceptable, or something close to it, then a  
 >> single new Option/define in any kernel Makefile which sets - 
 >> DPARALLELS will fix the problem.
 >
 > Hi George --
 >
 > Newer Parallels versions should give reasonable data in DMI tables.  
 > Can
 > you look into modifying your patch to automatically detect and disable
 > this section of code based on that information rather than adding
 > another compile-time option? See the pmf(4) man page for information  
 > on
 > retrieving DMI information from the driver.
 
 I'd say it's flat-out wrong to make this change at all, unless you're  
 specifically testing for buggy versions of Parallels when you apply  
 the work-around.
 
 This issue needs to be reported to Parallels so that they can fix it.   
 The work-around can lead to a significant performance penalty.
 
 
 >
 >
 > Cheers,
 > Jared
 >
 
 -- thorpej