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Re: [Libguestfs] [PATCH] v2v: virtio-win: include *.dll too



On Sun, Nov 08, 2015 at 10:15:31AM +0200, Yan Vugenfirer wrote:
> 
> > On 06 Nov 2015, at 08:51, Vadim Rozenfeld <vrozenfe redhat com> wrote:
> > 
> > On Thu, 2015-11-05 at 21:46 +0000, Richard W.M. Jones wrote:
> >> On Thu, Oct 29, 2015 at 11:05:42AM +1100, Vadim Rozenfeld wrote:
> >>> On Wed, 2015-10-28 at 14:53 +0300, Roman Kagan wrote:
> >>>>  1) tell which devices can be configured
> >>> Not sure that I fully understated your question. but if you are going to
> >>> create some sort of off-line automatic virtio-win drivers update
> >>> utility, then it shouldn't be too complicated. Firs of all you will need
> >>> to obtain the Windows kernel version by reading the following Registry
> >>> key - "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion". Let's say it
> >>> 6.3, which means that it is Win8.1 or WS2012R2, parsing "BuildLabEx"
> >>> string from the same hive will give you information about the platform
> >>> bitness. Next you need to go through inf files, and find "DriverVer"
> >>> string, like this one . taken from from vioscsi.inf
> >>> 
> >>> DriverVer=08/01/2015,62.72.104.10800
> >>> 
> >>> This string contains build time and version stamps. The version stamp
> >>> looks as follow "62.72.104.10800"
> >>> where 62 means a target Windows kernel version multiplied by 10. In this
> >>> case it is 6.2 which means Win8 or WS2012
> >>> 72 - the target host platform version multiplied bu 10 (was RHEL7.2)
> >>> 104 just a magic number, but it can be changed, don't make any
> >>> assumption based on this number.
> >>> 10800 our internal build number (build 108) multiplied by 100
> >> 
> >> Hi Vadim,
> >> 
> >> I've almost finished implementing this, but I have a couple of
> >> technical questions:
> >> 
> >> (1) How can we tell from the .inf file what architecture (x86 or
> >> amd64) the driver is for?  There is a [Manufacturer] section which
> >> looks hopeful, eg:
> >> 
> >>  [Manufacturer]
> >>  %RHEL%   = RHEL,NTAMD64
> >> 
> >> but the contents are not very consistent across all the .inf files I
> >> have access to.
> > 
> > Hi Richard,
> > 
> > It should be consistent. We do specify target architecture (amd64 or
> > x86) when stamping inf/inx files. IIRC, qemupciserial.inf is the only
> > exception, but it goes without binaries. In any case, if you are going
> > to use existing distribution media, you can rely on the media layout -
> > for example, if "amd64" is a part of your current path - you are in
> > 64-bit directory. 
> >> 
> >> (2) If we have a directory containing multiple drivers, can we assume
> >> that if any .inf file found matches the guest OS, then all those
> >> drivers can be installed?  So far this appears to be true.  
> > Yes, we will never mix 32 and 64 bit drivers into the same directory.
> > I swear:) 
> > 
> >> If not
> >> then we have to start associating drivers with .inf files, which seems
> >> a bit complicated.
> >> 
> >> (3) You write:
> >> 
> >>> If you found an inf file with the matching minor OS (6 in our case)
> >>> version and matching or less but close minor version number (2 vs 3)
> >>> then you are in the right directory.
> >> 
> >> When you say "close minor version number" is there a particular
> >> definition you have in mind?  eg. minor or minor-1 is OK?  Or do we
> >> have to consider all .inf files in totality and choose the nearest
> >> one?
> > Ideally, we should try finding the exact match. If not, we have to find
> > one with the same major version number and nearest minor number which is
> > smaller than the target one. For example, let's say we are looking for a
> > driver for Win8.1/WS2012R2, we know that both of them have kernel
> > version 6.3 . So, ideally we should to find inf file with the following
> > driver version string:
> > 
> > DriverVer=XX/YY/ZZZZ,63.AA.BBB.CCCCC
> > 
> > if we cannot find an inf file with such criteria, we should try finding
> > another one with the OS version 62 (which means that a driver was build
> > for kernel 6.2 Win8/WS2012 and technically should be compatible with
> > 6.3). So, we are looking for DriverVer which looks like this one:
> > DriverVer=XX/YY/ZZZZ,62.AA.BBB.CCCCC
> > 
> > Still no luck - decrease the target OS version to 61 and repeat.
> > 
> > For WDF drivers like balloon, vioserial, and rng you can go as far as
> > you can trying to find an appropriate driver. 
> > 
> > For miniport drivers like netkvm ( Yan, please confirm ), viostor and
> > vioscsi I wouldn't go too far. For example drivers designed to fork in
> > specific stacks at kernel version 5.1 (WinXP) can refuse working with
> > kernel 6.2 (Win8).
> 
> While NDIS miniport designed for NDIS 5.1 (XP) still can run on latest Windows, I wouldn’t do that. For NDIS 6.x (Windows 2008 and newer), we can use older drivers on new OS.
> But installing a driver for a newer OS on older OS might lead to driver miss-behaviour.

I'm wondering how people who don't rely on virt-v2v are supposed to
discover the virtio drivers for their guests?  This includes both those
who do it programmatically and those who locate the appropriate drivers
manually.

I mean, both manual and programmatic procedures should resolve to the
same set of drivers, and ideally the procedure should be the same,
declared official and documented.

I see no problem implementing any particular algorithm, no matter how
complex, in v2v, but I'd like to make sure that my colleagues who, say,
write a tool for unattended deployment of Windows guests, or others, who
manually set up their Windows VMs, arrive at the same configuration.

I tend to think that your original idea of sorting that out on the
driver build side, and storing the resulting drivers grouped by
Windows arch/version following a well-defined and stable naming
convention is a more reliable and universal solution.

Thanks,
Roman.


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