Arjan van de Ven wrote:
> On Tue, 2006-07-18 at 00:00 -0700, Chris Wright wrote:
>
>> +#ifndef CONFIG_XEN
>> movl %cr0, %eax
>> testl $0x4, %eax # EM (math emulation bit)
>> - jne device_not_available_emulate
>> - preempt_stop
>> - call math_state_restore
>> - jmp ret_from_exception
>> -device_not_available_emulate:
>> + je device_available_emulate
>> pushl $0 # temporary storage for ORIG_EIP
>> CFI_ADJUST_CFA_OFFSET 4
>> call math_emulate
>> addl $4, %esp
>> CFI_ADJUST_CFA_OFFSET -4
>> + jmp ret_from_exception
>> +device_available_emulate:
>> +#endif
>>
>
>
> Hi,
>
> can you explain what this chunk is for? It appears to be for the non-xen
> case due to the ifndef, yet it seems to visibly change the code for
> that... that deserves an explanation for sure ...
>
This inverts the logic of the test so that the lines:
preempt_stop
call math_state_restore
jmp ret_from_exception
can be hoisted out of the ifdef and shared in the Xen and non-Xen cases.
J
