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Date: Thu, 19 Jul 2012 18:18:04 -0500 From: Anthony Liguori <anthony@...emonkey.ws> To: KY Srinivasan <kys@...rosoft.com> CC: "Greg KH (gregkh@...uxfoundation.org)" <gregkh@...uxfoundation.org>, Paolo Bonzini <pbonzini@...hat.com>, "devel@...uxdriverproject.org" <devel@...uxdriverproject.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "virtualization@...ts.osdl.org" <virtualization@...ts.osdl.org> Subject: Re: 0xB16B00B5? Really? (was Re: Move hyperv out of the drivers/staging/ directory) On 07/19/2012 05:30 PM, KY Srinivasan wrote: > > >> -----Original Message----- >> From: Greg KH (gregkh@...uxfoundation.org) >> [mailto:gregkh@...uxfoundation.org] >> Sent: Thursday, July 19, 2012 6:02 PM >> To: KY Srinivasan >> Cc: Paolo Bonzini; devel@...uxdriverproject.org; linux-kernel@...r.kernel.org; >> virtualization@...ts.osdl.org >> Subject: Re: 0xB16B00B5? Really? (was Re: Move hyperv out of the >> drivers/staging/ directory) >> >> On Thu, Jul 19, 2012 at 09:22:53PM +0000, KY Srinivasan wrote: >>> >>> >>>> -----Original Message----- >>>> From: Greg KH (gregkh@...uxfoundation.org) >>>> [mailto:gregkh@...uxfoundation.org] >>>> Sent: Thursday, July 19, 2012 5:07 PM >>>> To: KY Srinivasan >>>> Cc: Paolo Bonzini; devel@...uxdriverproject.org; linux- >> kernel@...r.kernel.org; >>>> virtualization@...ts.osdl.org >>>> Subject: Re: 0xB16B00B5? Really? (was Re: Move hyperv out of the >>>> drivers/staging/ directory) >>>> >>>> On Thu, Jul 19, 2012 at 02:11:47AM +0000, KY Srinivasan wrote: >>>>> >>>>> >>>>>> -----Original Message----- >>>>>> From: Paolo Bonzini [mailto:paolo.bonzini@...il.com] On Behalf Of Paolo >>>>>> Bonzini >>>>>> Sent: Friday, July 13, 2012 6:23 AM >>>>>> To: KY Srinivasan >>>>>> Cc: Greg KH; devel@...uxdriverproject.org; linux-kernel@...r.kernel.org; >>>>>> virtualization@...ts.osdl.org >>>>>> Subject: 0xB16B00B5? Really? (was Re: Move hyperv out of the >>>> drivers/staging/ >>>>>> directory) >>>>>> >>>>>> Il 04/10/2011 21:34, Greg KH ha scritto: >>>>>>> diff --git a/drivers/staging/hv/hyperv_vmbus.h >>>> b/drivers/hv/hyperv_vmbus.h >>>>>>> similarity index 99% >>>>>>> rename from drivers/staging/hv/hyperv_vmbus.h >>>>>>> rename to drivers/hv/hyperv_vmbus.h >>>>>>> index 3d2d836..8261cb6 100644 >>>>>>> --- a/drivers/staging/hv/hyperv_vmbus.h >>>>>>> +++ b/drivers/hv/hyperv_vmbus.h >>>>>>> @@ -28,8 +28,7 @@ >>>>>>> #include<linux/list.h> >>>>>>> #include<asm/sync_bitops.h> >>>>>>> #include<linux/atomic.h> >>>>>>> - >>>>>>> -#include "hyperv.h" >>>>>>> +#include<linux/hyperv.h> >>>>>>> >>>>>>> /* >>>>>>> * The below CPUID leaves are present if >>>>>> VersionAndFeatures.HypervisorPresent >>>>>> >>>>>> git's rename detection snips away this gem: >>>>>> >>>>>> +#define HV_LINUX_GUEST_ID_LO 0x00000000 >>>>>> +#define HV_LINUX_GUEST_ID_HI 0xB16B00B5 >>>>>> +#define HV_LINUX_GUEST_ID (((u64)HV_LINUX_GUEST_ID_HI >>>>>> << 32) | \ >>>>>> + HV_LINUX_GUEST_ID_LO) >>>>>> >>>>>> Somone was trying to be funny, I guess. >>>>>> >>>>>> KY, I suppose you have access to Hyper-V code or can ask someone who >>>> does. >>>>>> Is this signature actually used in the Hyper-V host code? >>>>> >>>>> Paolo, >>>>> >>>>> As I noted earlier, this is just a guest ID that needs to be registered with the >>>>> hypervisor. Thanks for reporting this issue and on behalf of Microsoft, I >> would >>>>> like to apologize for this offensive string. I have submitted a patch to fix this >>>> issue. >>>> >>>> You only changed it to be in decimal, you did not change the id at all. >>>> Is there some reason why you can not change it? You said there was a >>>> reserved range of ids that could be used, perhaps just pick another one? >>>> What is the valid range that can be used here? >>> >>> Greg, >>> >>> As you know, this ID has been in use for a long time now. While the hypervisor >>> does not interpret the guest ID that is registered, I am not sure what >> dependencies >>> there might be on this value. >> >> Could you please go find out the answer to this? > > That is easier said than done. I have sent emails out asking this very question and I have > not received a definitive answer yet. Not knowing if and when I can get a definitive > answer here, I chose the least risky approach in my patch. >> >> If, as you originally stated, there is a range of values we can use, >> then we should probably use another one, right? > > On the Windows side this ID namespace is managed well. However on the Linux > side, we have really had this current ID in use for almost five years now. I am not > aware of any pool of IDs available for Linux usage except that Linux IDs be distinct from > the guest IDs in use by MSFT operating systems. If I were to change the guest ID, I would > probably want to comply with the MSFT guidance on constructing these IDs (although not > all fields may be relevant for Linux). Presumably, Hyper-V can deal with unexpected values here, no? Otherwise, it wouldn't be future proof against new types of guests. So worst case scenario, Hyper-V disables optimizations on Linux guests that report then new ID until they patch Hyper-V to know about the new ID. That seems like a reasonable trade off to me. I'm sure there's sufficient incentive to patch Hyper-V for this at Microsoft... Regards, Anthony Liguori > > Regards, > > K. Y > > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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