Re: XEN/IA64 VHPT support

Re: XEN/IA64 VHPT support

[Dong, Eddie]

Dan:
	Probably you can rely on us for the long format VHPT although
the detail plan is not done yet. BTW, for the hypercall, I am thinking
how it will be implemented in IA64 architecture. I think a straight
forward way is to use break instruction like linux system call, any idea
in your mind? 

Eddie


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kernel BUG error message.

[Perry Couprie]

Hoi,

When starting the kernel, i get the following error message.
What does it mean ?

Greeting Perry Couprie (Amsterdam Holland).


------------[ cut here ]------------
kernel BUG at <bad filename>:63120!
invalid operand: 0000 [#1]
PREEMPT DEBUG_PAGEALLOC
Modules linked in:
CPU:    0
EIP:    0061:[<c01091e9>]    Not tainted VLI
EFLAGS: 00013206   (2.6.10-xen0)
EIP is at resume_vm86+0x17/0x1a
eax: ffffffda   ebx: 00000000   ecx: 00000000   edx: 00000000
esi: 00000000   edi: 00000000   ebp: 00000000   esp: cd38df14
ds: 0000   es: 0000   ss: 0069
Process kmodule (pid: 2638, threadinfo=cd38c000 task=cd359b20)
Stack: 00004f00 00001423 0000c000 00023202 00000ffa 00001000 00001101 
00000000
       00000000 00000000 00000000 00000000 00000000 00000000 00000000 
00000000
       00000000 00000000 00000000 00000000 80000000 00000000 00000000 
00000000
Call Trace:
 [<c0109194>] syscall_call+0x7/0xb
Code: 01 0f 85 87 01 00 00 5b 59 5a 5e 5f 5d 58 1f 07 83 c4 04 cf c6 46 
01 00 5b 59 5a 5e 5f 5d 58 1f 07 89 04 24 b8 17 00 00 00 cd 82 <0f> 0b 
90 f6 c1 08 74 19 e8 7a 80 2a 00 c6 46 01 01
8b 4d 08 81



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Re: XEN/IA64 VHPT support

[Dan Magenheimer]

> 	Probably you can rely on us for the long format VHPT although
> the detail plan is not done yet. BTW, for the hypercall, I am thinking
> how it will be implemented in IA64 architecture. I think a straight
> forward way is to use break instruction like linux system call, any idea
> in your mind? 

Re LVHPT.  Please let me know if you work on it as it has been
something I've been wanting to get done for some time, mostly because
it will make simulations run faster too.  So if you don't get to
it soon, I might work on it, and it would be bad if we both
finished at the same time :-)

Re hypercalls.  Actually there are hypercalls already in Xen/ia64
and they do use the break instruction.  It's just that the domain
calls them indirectly so perhaps they are better called "hyperthunks"
("Thunk" is a rarely used compiler term which originated in Algol 60
that means: "code that is used to convert calls to one interface
into calls to another"):

When a domain is created, fake EFI/SAL/PAL (firmware) calls are created
that contain the hypercalls.  Thus when domain0 invokes an EFI/SAL/PAL
call, it calls a "stub" routine that invokes a break instruction/fault
that is recognized in Xen/ia64 as a hypercall, with arguments passed
in general registers (unlike Xen/x86 which passes hypercall arguments
in memory).

You may want to step through a domain0 firmware call to see this work.
If I recall correctly, the code that creates the hyperthunks is
in arch/ia64/dom_fw.c

While my intent is to use the same mechanism (breaks) for "real" hypercalls,
I also want to explore the use of fast system calls (recently added
in Linux/ia64 by David Mosberger) using the epc instruction in certain
cases.

Dan




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RE: kernel BUG error message.

[Ian Pratt]

You need to give us a more information. Which version of Xen, what
kernel? I presume this running in domain 0 (i.e. when you start the
machine) rather than a subsequent virtual machine that you started. What
CPU does your machine have? Are you trying to start an Xserver or boot
to a command line? (if the former, try the latter and start X manually

Ian

> When starting the kernel, i get the following error message.
> What does it mean ?
> 
> Greeting Perry Couprie (Amsterdam Holland).
> 
> 
> ------------[ cut here ]------------
> kernel BUG at <bad filename>:63120!
> invalid operand: 0000 [#1]
> PREEMPT DEBUG_PAGEALLOC
> Modules linked in:
> CPU:    0
> EIP:    0061:[<c01091e9>]    Not tainted VLI
> EFLAGS: 00013206   (2.6.10-xen0)
> EIP is at resume_vm86+0x17/0x1a
> eax: ffffffda   ebx: 00000000   ecx: 00000000   edx: 00000000
> esi: 00000000   edi: 00000000   ebp: 00000000   esp: cd38df14
> ds: 0000   es: 0000   ss: 0069
> Process kmodule (pid: 2638, threadinfo=cd38c000 task=cd359b20)
> Stack: 00004f00 00001423 0000c000 00023202 00000ffa 00001000 00001101 
> 00000000
>        00000000 00000000 00000000 00000000 00000000 00000000 00000000 
> 00000000
>        00000000 00000000 00000000 00000000 80000000 00000000 00000000 
> 00000000
> Call Trace:
>  [<c0109194>] syscall_call+0x7/0xb
> Code: 01 0f 85 87 01 00 00 5b 59 5a 5e 5f 5d 58 1f 07 83 c4 
> 04 cf c6 46 
> 01 00 5b 59 5a 5e 5f 5d 58 1f 07 89 04 24 b8 17 00 00 00 cd 
> 82 <0f> 0b 
> 90 f6 c1 08 74 19 e8 7a 80 2a 00 c6 46 01 01
> 8b 4d 08 81
> 
> 
> 
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> _______________________________________________
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> Xen-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/xen-devel
> 


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