Re: [RFC PATCH 16/33] Add support for Xen to entry.S.

From: Arjan van de Ven
Date: Tue Jul 18 2006 - 06:11:14 EST


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 ...

Greetings,
Arjan van de Ven

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