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/*
* This file is part of the coreboot project.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
__fpu_start:
/* Preserve BIST. */
movl %eax, %ebp
/*
* Clear the CR0[2] bit (the "Emulation" flag, EM).
*
* This indicates that the processor has an (internal or external)
* x87 FPU, i.e. floating point operations will be executed by the
* hardware (and not emulated in software).
*
* Additionally, if this bit is not cleared, MMX/SSE instructions won't
* work, i.e., they will trigger an invalid opcode exception (#UD).
*/
movl %cr0, %eax
andl $~(1 << 2), %eax
movl %eax, %cr0
/* Restore BIST. */
movl %ebp, %eax
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