programme header

programme header

[ishare]

On Mon, Mar 18, 2013 at 03:02:02PM -0700, Ian Lance Taylor wrote:
> On Sun, Mar 17, 2013 at 1:54 AM, ishare <june.tune.sea@gmail.com> wrote:
> >
> >
> >   when product a .so liberary , if there is not a programme header in the linker script file,
> >   will the linker automaticlly generate a deault one for use  ?
> 
> Yes.
> 
> >   If I write the programme header manully , need I write it before writing  section command ?
> 
> No.

  I am linking my kernel by a link script. its contens is as below:
  
*********************************************************************

VSYSCALL_BASE = 0xffffe000;

SECTIONS
{
  . = VSYSCALL_BASE + SIZEOF_HEADERS;

  .hash           : { *(.hash) }		:text
  .dynsym         : { *(.dynsym) }
  .dynstr         : { *(.dynstr) }
  .gnu.version    : { *(.gnu.version) }
  .gnu.version_d  : { *(.gnu.version_d) }
  .gnu.version_r  : { *(.gnu.version_r) }

  /* This linker script is used both with -r and with -shared.
     For the layouts to match, we need to skip more than enough
     space for the dynamic symbol table et al.  If this amount
     is insufficient, ld -shared will barf.  Just increase it here.  */
  . = VSYSCALL_BASE + 0x400;

  .text           : { *(.text) }		:text =0x90909090

  .eh_frame_hdr   : { *(.eh_frame_hdr) }	:text :eh_frame_hdr
  .eh_frame       : { KEEP (*(.eh_frame)) }	:text
  .dynamic        : { *(.dynamic) }	  	:text :dynamic
  .useless        : {
  		  *(.got.plt) *(.got)
		  *(.data .data.* .gnu.linkonce.d.*)
		  *(.dynbss)
		  *(.bss .bss.* .gnu.linkonce.b.*)
  }							:text
}

PHDRS
{
  text PT_LOAD FILEHDR PHDRS FLAGS(5); /* PF_R|PF_X */
  dynamic PT_DYNAMIC FLAGS(4); /* PF_R */
  eh_frame_hdr 0x6474e550; /* PT_GNU_EH_FRAME, but ld doesn't match the name */
}

*******************************************************************************

 I think it will work ,but ld report that "No enough room for programme header",what is the reason?
 what should I do ?

 thanks!



> Ian

programme header

[Valdis.Kletnieks at vt.edu]

On Tue, 19 Mar 2013 09:38:49 +0800, ishare said:

>   I am linking my kernel by a link script. its contens is as below:

>  I think it will work ,but ld report that "No enough room for programme header",what is the reason?
>  what should I do ?

The first thing you do is ask yourself why you're using a link script
of your own, when most architectures come with a working link script already.

The second thing you do is *read the script* - there's a big copmment in there:

  /* This linker script is used both with -r and with -shared.
     For the layouts to match, we need to skip more than enough
     space for the dynamic symbol table et al.  If this amount
     is insufficient, ld -shared will barf.  Just increase it here.  */

Hope that helps.
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programme header

[ishare]

On Mon, Mar 18, 2013 at 10:41:45PM -0400, Valdis.Kletnieks at vt.edu wrote:
> On Tue, 19 Mar 2013 09:38:49 +0800, ishare said:
> 
> >   I am linking my kernel by a link script. its contens is as below:
> 
> >  I think it will work ,but ld report that "No enough room for programme header",what is the reason?
> >  what should I do ?
> 
> The first thing you do is ask yourself why you're using a link script
> of your own, when most architectures come with a working link script already.
> 
> The second thing you do is *read the script* - there's a big copmment in there:
> 
>   /* This linker script is used both with -r and with -shared.
>      For the layouts to match, we need to skip more than enough
>      space for the dynamic symbol table et al.  If this amount
>      is insufficient, ld -shared will barf.  Just increase it here.  */
   
  because I need to generate a .so for sysenter used 

  thanks!


> 
> Hope that helps.

programme header

[Valdis.Kletnieks at vt.edu]

On Tue, 19 Mar 2013 12:44:36 +0800, ishare said:

>   because I need to generate a .so for sysenter used

And that solves what problem for you, exactly?

Consider that most architectures that use sysenter manage to do so
without having to worry about a .so for it (or if they really do need
one, they already create a .so).  So what problem are you trying to
solve by using a .so?
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