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| author | Alan Kao <alankao@andestech.com> | 2018-10-09 04:18:34 +0200 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@sifive.com> | 2018-10-23 02:02:23 +0200 |
| commit | 9411ec60c23d868124d9c1b1d491937aebe07afa (patch) | |
| tree | b099a760ac5b284dd79281ded728e35ec30d2e77 /arch/riscv/include/asm/switch_to.h | |
| parent | Allow to disable FPU support (diff) | |
| download | linux-9411ec60c23d868124d9c1b1d491937aebe07afa.tar.xz linux-9411ec60c23d868124d9c1b1d491937aebe07afa.zip | |
Auto-detect whether a FPU exists
We expect that a kernel with CONFIG_FPU=y can still support no-FPU
machines. To do so, the kernel should first examine the existence of a
FPU, then do nothing if a FPU does exist; otherwise, it should
disable/bypass all FPU-related functions.
In this patch, a new global variable, has_fpu, is created and determined
when parsing the hardware capability from device tree during booting.
This variable is used in those FPU-related functions.
Signed-off-by: Alan Kao <alankao@andestech.com>
Cc: Greentime Hu <greentime@andestech.com>
Cc: Vincent Chen <vincentc@andestech.com>
Cc: Zong Li <zong@andestech.com>
Cc: Nick Hu <nickhu@andestech.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Diffstat (limited to 'arch/riscv/include/asm/switch_to.h')
| -rw-r--r-- | arch/riscv/include/asm/switch_to.h | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/arch/riscv/include/asm/switch_to.h b/arch/riscv/include/asm/switch_to.h index 093050b03543..733559083f24 100644 --- a/arch/riscv/include/asm/switch_to.h +++ b/arch/riscv/include/asm/switch_to.h @@ -56,13 +56,12 @@ static inline void __switch_to_aux(struct task_struct *prev, fstate_restore(next, task_pt_regs(next)); } -#define DEFAULT_SSTATUS (SR_SPIE | SR_FS_INITIAL) - +extern bool has_fpu; #else +#define has_fpu false #define fstate_save(task, regs) do { } while (0) #define fstate_restore(task, regs) do { } while (0) #define __switch_to_aux(__prev, __next) do { } while (0) -#define DEFAULT_SSTATUS (SR_SPIE | SR_FS_OFF) #endif extern struct task_struct *__switch_to(struct task_struct *, @@ -72,7 +71,8 @@ extern struct task_struct *__switch_to(struct task_struct *, do { \ struct task_struct *__prev = (prev); \ struct task_struct *__next = (next); \ - __switch_to_aux(__prev, __next); \ + if (has_fpu) \ + __switch_to_aux(__prev, __next); \ ((last) = __switch_to(__prev, __next)); \ } while (0) |