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Fw: Re: Re: [Xen-devel] A question related with symbol reference?



 
 
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@xxxxxxxxxx; 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@xxxxxxxxxx> 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 
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