A question related with symbol reference?

A question related with symbol reference?

[房海峰]

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hi, my friends:

recently, i am reading the source codes about hypercall.

First, i study a simple hypercall, for example, the "do_xen_version".

In "xen-3.1.0-src\xen\common\kernel.c", the definition of "do_xen_version" is:

DO(xen_version) (int cmd, XEN_GUEST_HANDLE(void) arg)
{
....
}

according to the " #define DO(fn) long do_##fn ", the expanded form is "do_xen_version (...)".

then, in the "xen-3.1.0-src\xen\arch\x86\x86_32\entry.S", there is an item in the "hypercall_table", like this:

ENTRY(hypercall_table)
....
.long do_xen_version
....


as we all known, for a symbol reference of function there need to be a header file contained, or a "global" declaration.

By searching the header files, i found the file, "xen-3.1.0-src\xen\include\xen\hypercall.h" that declared the function in a form as follows:

extern long
do_xen_version(
int cmd,
XEN_GUEST_HANDLE(void) arg);

But, i can not find where the file "hypercall.h" is contained in order to link it with the reference of "do_xen_version" in the "entry.S"

So, please help me, or give me some advice.

thanks advance.

2008-03-18 



房海峰 

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A question related with symbol reference?

[房海峰]

[-- Attachment #1.1: Type: text/plain, Size: 1154 bytes --]

hi, my friends:

recently, i am reading the source codes about hypercall.

First, i study a simple hypercall, for example, the "do_xen_version".

In "xen-3.1.0-src\xen\common\kernel.c", the definition of "do_xen_version" is:

DO(xen_version) (int cmd, XEN_GUEST_HANDLE(void) arg)
{
....
}

according to the " #define DO(fn) long do_##fn ", the expanded form is "do_xen_version (...)".

then, in the "xen-3.1.0-src\xen\arch\x86\x86_32\entry.S", there is an item in the "hypercall_table", like this:

ENTRY(hypercall_table)
....
.long do_xen_version
....


as we all known, for a symbol reference of function there need to be a header file contained, or a "global" declaration.

By searching the header files, i found the file, "xen-3.1.0-src\xen\include\xen\hypercall.h" that declared the function in a form as follows:

extern long
do_xen_version(
int cmd,
XEN_GUEST_HANDLE(void) arg);

But, i can not find where the file "hypercall.h" is contained in order to link it with the reference of "do_xen_version" in the "entry.S"

So, please help me, or give me some advice.

thanks advance.

2008-03-18 



房海峰 

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A question related with symbol reference?

[房海峰]

[-- Attachment #1.1: Type: text/plain, Size: 1154 bytes --]

hi, my friends:

recently, i am reading the source codes about hypercall.

First, i study a simple hypercall, for example, the "do_xen_version".

In "xen-3.1.0-src\xen\common\kernel.c", the definition of "do_xen_version" is:

DO(xen_version) (int cmd, XEN_GUEST_HANDLE(void) arg)
{
....
}

according to the " #define DO(fn) long do_##fn ", the expanded form is "do_xen_version (...)".

then, in the "xen-3.1.0-src\xen\arch\x86\x86_32\entry.S", there is an item in the "hypercall_table", like this:

ENTRY(hypercall_table)
....
.long do_xen_version
....


as we all known, for a symbol reference of function there need to be a header file contained, or a "global" declaration.

By searching the header files, i found the file, "xen-3.1.0-src\xen\include\xen\hypercall.h" that declared the function in a form as follows:

extern long
do_xen_version(
int cmd,
XEN_GUEST_HANDLE(void) arg);

But, i can not find where the file "hypercall.h" is contained in order to link it with the reference of "do_xen_version" in the "entry.S"

So, please help me, or give me some advice.

thanks advance.

2008-03-18 



房海峰 

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Re: A question related with symbol reference?

[Zang Hongyong]

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anyone can help?　　
I'm confused too.

======== 2008-03-18 14:04:50 您在来信中写道： ========

hi, my friends:

recently, i am reading the source codes about hypercall.

First, i study a simple hypercall, for example, the "do_xen_version".

In "xen-3.1.0-src\xen\common\kernel.c", the definition of "do_xen_version" is:

DO(xen_version) (int cmd, XEN_GUEST_HANDLE(void) arg)
{
....
}

according to the " #define DO(fn) long do_##fn ", the expanded form is "do_xen_version (...)".

then, in the "xen-3.1.0-src\xen\arch\x86\x86_32\entry.S", there is an item in the "hypercall_table", like this:

ENTRY(hypercall_table)
....
.long do_xen_version
....


as we all known, for a symbol reference of function there need to be a header file contained, or a "global" declaration.

By searching the header files, i found the file, "xen-3.1.0-src\xen\include\xen\hypercall.h" that declared the function in a form as follows:

extern long
do_xen_version(
int cmd,
XEN_GUEST_HANDLE(void) arg);

But, i can not find where the file "hypercall.h" is contained in order to link it with the reference of "do_xen_version" in the "entry.S"

So, please help me, or give me some advice.

thanks advance.

2008-03-18 



房海峰 



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Re: A question related with symbol reference?

[Keir Fraser]

Assembly code does not need a function prototype or indeed any label
declaration to be able to reference that function/label.

 -- Keir

On 18/3/08 06:19, "Zang Hongyong" <zanghongyong@ncic.ac.cn> wrote:

> anyone can help?　　
> I'm confused too.
> 
> ======== 2008-03-18 14:04:50 您在来信中写道： ========
> 
> hi, my friends:
> 
> recently, i am reading the source codes about hypercall.
> 
> First, i study a simple hypercall, for example, the "do_xen_version".
> 
> In "xen-3.1.0-src\xen\common\kernel.c", the definition of "do_xen_version" is:
> 
> DO(xen_version) (int cmd, XEN_GUEST_HANDLE(void) arg)
> {
> ....
> }
> 
> according to the " #define DO(fn) long do_##fn ", the expanded form is
> "do_xen_version (...)".
> 
> then, in the "xen-3.1.0-src\xen\arch\x86\x86_32\entry.S", there is an item in
> the "hypercall_table", like this:
> 
> ENTRY(hypercall_table)
> ....
> .long do_xen_version
> ....
> 
> 
> as we all known, for a symbol reference of function there need to be a header
> file contained, or a "global" declaration.
> 
> By searching the header files, i found the file,
> "xen-3.1.0-src\xen\include\xen\hypercall.h" that declared the function in a
> form as follows:
> 
> extern long
> do_xen_version(
> int cmd,
> XEN_GUEST_HANDLE(void) arg);
> 
> But, i can not find where the file "hypercall.h" is contained in order to link
> it with the reference of "do_xen_version" in the "entry.S"
> 
> So, please help me, or give me some advice.
> 
> thanks advance.
> 
> 2008-03-18 
> 
> 
> 
> 房海峰 
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel

Fw: Re: Re: A question related with symbol reference?

[房海峰]

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2008-03-18



房海峰



发件人： 房海峰
发送时间： 2008-03-18 16:49:06
收件人： Keir Fraser
抄送： 
主题： Re: Re: [Xen-devel] A question related with symbol reference?

I have been programmed assembly code with "nasm" language.
in "nasm", when you refere to a function/label that come from another file, you should make a declaration of the function with "extern" keywords in advance.

i don't know whether "at&t" assembly language is different with "nasm"?

thanks again!


2008-03-18 



房海峰 



发件人： Keir Fraser 
发送时间： 2008-03-18  16:12:41 
收件人： Zang Hongyong; fanghaifeng@ncic.ac.cn; xen-devel 
抄送： 
主题： Re: [Xen-devel] A question related with symbol reference? 
Assembly code does not need a function prototype or indeed any label
declaration to be able to reference that function/label.
 -- Keir
On 18/3/08 06:19, "Zang Hongyong" <zanghongyong@ncic.ac.cn> wrote:
> anyone can help?　　
> I'm confused too.
> 
> ======== 2008-03-18 14:04:50 您在来信中写道： ========
> 
> hi, my friends:
> 
> recently, i am reading the source codes about hypercall.
> 
> First, i study a simple hypercall, for example, the "do_xen_version".
> 
> In "xen-3.1.0-src\xen\common\kernel.c", the definition of "do_xen_version" is:
> 
> DO(xen_version) (int cmd, XEN_GUEST_HANDLE(void) arg)
> {
> ....
> }
> 
> according to the " #define DO(fn) long do_##fn ", the expanded form is
> "do_xen_version (...)".
> 
> then, in the "xen-3.1.0-src\xen\arch\x86\x86_32\entry.S", there is an item in
> the "hypercall_table", like this:
> 
> ENTRY(hypercall_table)
> ....
> .long do_xen_version
> ....
> 
> 
> as we all known, for a symbol reference of function there need to be a header
> file contained, or a "global" declaration.
> 
> By searching the header files, i found the file,
> "xen-3.1.0-src\xen\include\xen\hypercall.h" that declared the function in a
> form as follows:
> 
> extern long
> do_xen_version(
> int cmd,
> XEN_GUEST_HANDLE(void) arg);
> 
> But, i can not find where the file "hypercall.h" is contained in order to link
> it with the reference of "do_xen_version" in the "entry.S"
> 
> So, please help me, or give me some advice.
> 
> thanks advance.
> 
> 2008-03-18 
> 
> 
> 
> 房海峰 
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel

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Re: A question related with symbol reference?

[Keir Fraser]

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The EXTERN directive is specific to nasm.

 -- Keir

On 18/3/08 08:49, "房海峰" <fanghaifeng@ncic.ac.cn> wrote:

> I have been programmed assembly code with "nasm" language.
> in "nasm", when you refere to a function/label that come from another file,
> you should make a declaration of the function with "extern" keywords in
> advance.
>  
> i don't know whether "at&t" assembly language is different with "nasm"?
>  
> thanks again!



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Re: Re: A question related with symbol reference?

[房海峰]

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maybe! i will study "at&t" indepth.

thank you for your reply.


2008-03-18 



房海峰 



发件人： Keir Fraser 
发送时间： 2008-03-18  16:35:27 
收件人： fanghaifeng@ncic.ac.cn; xen-devel 
抄送： 
主题： Re: [Xen-devel] A question related with symbol reference? 
 
The EXTERN directive is specific to nasm.

 -- Keir

On 18/3/08 08:49, "^[$BK<3$Jv^[(B" <fanghaifeng@ncic.ac.cn> wrote:


I have been programmed assembly code with "nasm" language.
in "nasm", when you refere to a function/label that come from another file, you should make a declaration of the function with "extern" keywords in advance.

i don't know whether "at&t" assembly language is different with "nasm"?

thanks again!

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