Mixing patches

Mixing patches

[Tom Cranbrook]

Are there any known problems with mixing Xen patches with any other kernel
patches?





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Re: Mixing patches

[Mark A. Williamson]

> Are there any known problems with mixing Xen patches with any other kernel
> patches?

Most things should apply OK.  If the patch touches the i386 architecture code 
then you'll want to run it through something like "sed 's/i386/xen/g".  If it 
touches certain parts of this code that are substantially different under Xen 
then it might need explicit porting.

Some complicated patching scripts (e.g. for some iSCSI module, IIRC) have  
many hardcoded assumptions about the i386 architecture and it might be easier 
to just rename the Xen architecture code to i386 in order to fool the 
patch ;-)  There's some script or makefile target provided with Xen for doing 
these renames.

Best approach is probably to try it and see what happens ;-)

Mark

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Re: Mixing patches

[Tom Cranbrook]

>> Are there any known problems with mixing Xen patches with any other
kernel
>> patches?
>
>Most things should apply OK.  If the patch touches the i386 architecture
code 
>then you'll want to run it through something like "sed 's/i386/xen/g".  If
it 
>touches certain parts of this code that are substantially different under
Xen 
>then it might need explicit porting.
>

<groan>  Well, it certainly looks like it touches arch.

Here's a patch log:

patching file kernel/exit.c
patching file kernel/fork.c
patching file kernel/sched.c
patching file mm/vmscan.c
patching file arch/i386/Kconfig
patching file arch/i386/kernel/apm.c
patching file arch/i386/kernel/cpu/common.c
patching file arch/i386/kernel/entry.S
patching file arch/i386/kernel/head.S
patching file arch/i386/kernel/process.c
patching file arch/i386/kernel/signal.c
patching file arch/i386/kernel/vm86.c
patching file arch/i386/Makefile
patching file arch/i386/mki/Makefile
patching file arch/i386/mki/mki.c
patching file arch/i386/mm/fault.c
patching file include/asm-i386/desc.h
patching file include/asm-i386/mki.h
patching file include/asm-i386/mkiversion.h
patching file include/asm-i386/segment.h
patching file include/asm-i386/thread_info.h
patching file include/linux/init_task.h
patching file include/linux/sched.h
patching file arch/i386/Makefile
patching file arch/i386/mki-adapter/get-version.c
patching file arch/i386/mki-adapter/LICENSE
patching file arch/i386/mki-adapter/Makefile
patching file arch/i386/mki-adapter/mki22.c
patching file arch/i386/mki-adapter/mki24.c
patching file arch/i386/mki-adapter/mki-adapter.h
patching file arch/i386/mki-adapter/mkifunc.h
patching file arch/i386/mki-adapter/mki-main.c
patching file arch/i386/mki-adapter/mkimki.c
patching file arch/i386/mki-adapter/mkivnet.c
patching file arch/i386/mki-adapter/README
patching file arch/i386/mki-adapter/timer.c
patching file arch/i386/mki-adapter/vneteth.h
patching file arch/i386/mki-adapter/vnetint-pub.h

This is a patch for Netraverse's Win4Lin.  I am trying to figure out a way
to get an instance of Win95 running on a netsork server for several legacy
apps.  I could devote a machine to it, but the Xen VM idea and migrating
server images is so compelling that I really wish I can do this in a
domain.





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Re: Mixing patches

[Rik van Riel]

On Mon, 4 Oct 2004, Tom Cranbrook wrote:

> This is a patch for Netraverse's Win4Lin.  I am trying to figure out a way
> to get an instance of Win95 running on a netsork server for several legacy
> apps.  I could devote a machine to it, but the Xen VM idea and migrating
> server images is so compelling that I really wish I can do this in a
> domain.

In order to emulate windows, chances are win4lin needs to
play with segments and LDT descriptors.  Fat chance that'll
work inside an unmodified Xen ...

-- 
"Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it." - Brian W. Kernighan



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Re: Mixing patches

[Tom Cranbrook]

>On Mon, 4 Oct 2004, Tom Cranbrook wrote:
>
>> This is a patch for Netraverse's Win4Lin. 
>
>In order to emulate windows, chances are win4lin needs to
>play with segments and LDT descriptors.  Fat chance that'll
>work inside an unmodified Xen ...


Hummm ,,  I've examined both patches pretty closely and I don't see any
obvious conflicts.  I'm going to try to build a win4lin patch modified to
apply to the post xen patch tree.  Hopefully, I'll just have to move the
arch/i386 files and patches to arch/xen/i386.  Any problem with this
strategy?





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Re: Mixing patches

[Ian Pratt]

> >> This is a patch for Netraverse's Win4Lin. 
> >
> >In order to emulate windows, chances are win4lin needs to
> >play with segments and LDT descriptors.  Fat chance that'll
> >work inside an unmodified Xen ...
> 
> Hummm ,,  I've examined both patches pretty closely and I don't see any
> obvious conflicts.  I'm going to try to build a win4lin patch modified to
> apply to the post xen patch tree.  Hopefully, I'll just have to move the
> arch/i386 files and patches to arch/xen/i386.  Any problem with this
> strategy?

I haven't looked at the patch, but it sounds like it would want
to do some pretty gross stuff. 

As a quick way to apply the patch, you might want to take a look
at the fakei386xen script in tools/misc. It basically renames
arch xen to arch i386 so the patch without modification. I wrote
it to enable me to build an external module supplied with a very
dumb Makefile.


Ian


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Re: Mixing patches

[Tom Cranbrook]

>I haven't looked at the patch, but it sounds like it would want
>to do some pretty gross stuff. 
>
>As a quick way to apply the patch, you might want to take a look
>at the fakei386xen script in tools/misc. It basically renames
>arch xen to arch i386 so the patch without modification. I wrote
>it to enable me to build an external module supplied with a very
>dumb Makefile.
>
>

Well, the script certainly ends up the equivilant of my first suggestion,
but a number of the files the w4l patch expects are gone.  This is a list
of files that it touches:

patching file kernel/sched.c
patching file mm/vmscan.c
patching file arch/i386/Kconfig
patching file arch/i386/kernel/apm.c
patching file arch/i386/kernel/cpu/common.c
patching file arch/i386/kernel/entry.S
patching file arch/i386/kernel/head.S
patching file arch/i386/kernel/process.c
patching file arch/i386/kernel/signal.c
patching file arch/i386/kernel/vm86.c
patching file arch/i386/Makefile
patching file arch/i386/mki/Makefile
patching file arch/i386/mki/mki.c
patching file arch/i386/mm/fault.c
patching file include/asm-i386/desc.h
patching file include/asm-i386/mki.h
patching file include/asm-i386/mkiversion.h
patching file include/asm-i386/segment.h
patching file include/asm-i386/thread_info.h
patching file include/linux/init_task.h
patching file include/linux/sched.h

Most of this seems to be hooks to a branch added to arch/i386 called
mki-adaptor in a second pacth.  This appears to be the interface to
netraverse's binary.  

Did all the i386 specific stuff move to the xen kernel?  I thought that the
idea of paravirtualization was the simularity between the abstraction and
the hardware.  Are these files things that have been moved to the xen
kernel and abstracted out of the domain environment?





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