Messages in this thread Patch in this message | | | From | riel@redhat ... | Subject | [RFC PATCH 01/11] x86,fpu: document the data structures a little | Date | Sun, 11 Jan 2015 16:46:23 -0500 |
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From: Rik van Riel <riel@redhat.com>
Add some documentation to data structures used for FPU context switching.
Signed-off-by: Rik van Riel <riel@redhat.com> --- arch/x86/include/asm/processor.h | 9 +++++++-- arch/x86/kernel/cpu/common.c | 1 + 2 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index a092a0c..17bd8a0 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -400,6 +400,11 @@ struct xsave_struct { /* new processor state extensions will go here */ } __attribute__ ((packed, aligned (64))); +/* + * The FPU state used depends on the capabilities of the hardware; the + * registers used for vector instructions on newer hardware are included + * in the FPU state. + */ union thread_xstate { struct i387_fsave_struct fsave; struct i387_fxsave_struct fxsave; @@ -408,8 +413,8 @@ union thread_xstate { }; struct fpu { - unsigned int last_cpu; - unsigned int has_fpu; + unsigned int last_cpu; /* FPU state last loaded on this CPU */ + unsigned int has_fpu; /* FPU state in current use on CPU */ union thread_xstate *state; }; diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index c604965..36837bb 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1143,6 +1143,7 @@ DEFINE_PER_CPU(unsigned int, irq_count) __visible = -1; DEFINE_PER_CPU(int, __preempt_count) = INIT_PREEMPT_COUNT; EXPORT_PER_CPU_SYMBOL(__preempt_count); +/* Task that currently has its FPU state loaded on the CPU. */ DEFINE_PER_CPU(struct task_struct *, fpu_owner_task); /* -- 1.9.3
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