[Devel] Re: How to enable SYSENTER/SYSEXIT in glibc-2.7?

[Linus Torvalds]

On Mon, 13 Apr 2009, Guofu Xiang wrote:
> 
>      (gdb) disas __kernel_vsyscall
>      Dump of assembler code for function __kernel_vsyscall:
>      0xb7f7a400 <__kernel_vsyscall+0>:       int    $0x80
>      0xb7f7a402 <__kernel_vsyscall+2>:       ret
>      End of assembler dump.

(gdb) disassemble __kernel_vsyscall
Dump of assembler code for function __kernel_vsyscall:
0xb8046414 <__kernel_vsyscall+0>:	push   %ecx
0xb8046415 <__kernel_vsyscall+1>:	push   %edx
0xb8046416 <__kernel_vsyscall+2>:	push   %ebp
0xb8046417 <__kernel_vsyscall+3>:	mov    %esp,%ebp
0xb8046419 <__kernel_vsyscall+5>:	sysenter 
0xb804641b <__kernel_vsyscall+7>:	nop    
0xb804641c <__kernel_vsyscall+8>:	nop    
0xb804641d <__kernel_vsyscall+9>:	nop    
0xb804641e <__kernel_vsyscall+10>:	nop    
0xb804641f <__kernel_vsyscall+11>:	nop    
0xb8046420 <__kernel_vsyscall+12>:	nop    
0xb8046421 <__kernel_vsyscall+13>:	nop    
0xb8046422 <__kernel_vsyscall+14>:	jmp    0xb8046417 <__kernel_vsyscall+3>
0xb8046424 <__kernel_vsyscall+16>:	pop    %ebp
0xb8046425 <__kernel_vsyscall+17>:	pop    %edx
0xb8046426 <__kernel_vsyscall+18>:	pop    %ecx
0xb8046427 <__kernel_vsyscall+19>:	ret    

>      The system call is implemented by int $80h, rather than SYSENTER. What
> is the reason? How to set SYSENTER as the default implementation of system
> call? Thank you for your response!

What CPU do you have?  We only enable sysenter on CPU's that support them 
well.

		Linus
_______________________________________________
Containers mailing list
Containers at lists.linux-foundation.org
https://lists.linux-foundation.org/mailman/listinfo/containers