arch/arm/nwfpe/ChangeLog

Source file repositories/reference/linux-study-clean/arch/arm/nwfpe/ChangeLog

File Facts

System
Linux kernel
Corpus path
arch/arm/nwfpe/ChangeLog
Extension
[no extension]
Size
4406 bytes
Lines
92
Domain
Architecture Layer
Bucket
arch/arm
Inferred role
Architecture Layer: arch/arm
Status
atlas-only

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

2003-03-22  Ralph Siemsen <ralphs@netwinder.org>
	* Reformat all but softfloat files to get a consistent coding style.
	  Used "indent -kr -i8 -ts8 -sob -l132 -ss" and a few manual fixups.
	* Removed dead code and fixed function protypes to match definitions.
	* Consolidated use of (opcode && MASK_ARITHMETIC_OPCODE) >> 20.
	* Make 80-bit precision a compile-time option. (1%)
	* Only initialize FPE state once in repeat-FP situations. (6%)

2002-01-19  Russell King <rmk@arm.linux.org.uk>

	* fpa11.h - Add documentation
	          - remove userRegisters pointer from this structure.
	          - add new method to obtain integer register values.
	* softfloat.c - Remove float128
	* softfloat.h - Remove float128
	* softfloat-specialize - Remove float128

	* The FPA11 structure is not a kernel-specific data structure.
	  It is used by users of ptrace to examine the values of the
	  floating point registers.  Therefore, any changes to the
	  FPA11 structure (size or position of elements contained
	  within) have to be well thought out.

	* Since 128-bit float requires the FPA11 structure to change
	  size, it has been removed.  128-bit float is currently unused,
	  and needs various things to be re-worked so that we won't
	  overflow the available space in the task structure.

	* The changes are designed to break any patch that goes on top
	  of this code, so that the authors properly review their changes.

1999-08-19  Scott Bambrough  <scottb@netwinder.org>

	* fpmodule.c - Changed version number to 0.95
	* fpa11.h - modified FPA11, FPREG structures
	* fpa11.c - Changes due to FPA11, FPREG structure alterations.
	* fpa11_cpdo.c - Changes due to FPA11, FPREG structure alterations.
	* fpa11_cpdt.c - Changes due to FPA11, FPREG structure alterations.
	* fpa11_cprt.c - Changes due to FPA11, FPREG structure alterations.
	* single_cpdo.c - Changes due to FPA11, FPREG structure alterations.
	* double_cpdo.c - Changes due to FPA11, FPREG structure alterations.
	* extended_cpdo.c - Changes due to FPA11, FPREG structure alterations.

	* I discovered several bugs.  First and worst is that the kernel
	  passes in a pointer to the FPE's state area.	This is defined
	  as a struct user_fp (see user.h).  This pointer was cast to a
	  FPA11*.  Unfortunately FPA11 and user_fp are of different sizes;
	  user_fp is smaller.  This meant that the FPE scribbled on things
	  below its area, which is bad, as the area is in the thread_struct
	  embedded in the process task structure.  Thus we were scribbling
	  over one of the most important structures in the entire OS.

	* user_fp and FPA11 have now been harmonized.  Most of the changes
	  in the above code were dereferencing problems due to moving the
	  register type out of FPREG, and getting rid of the union variable
	  fpvalue.

	* Second I noticed resetFPA11 was not always being called for a
	  task.  This should happen on the first floating point exception
	  that occurs.	It is controlled by init_flag in FPA11.  The
	  comment in the code beside init_flag state the kernel guarantees
	  this to be zero.  Not so.  I found that the kernel recycles task
	  structures, and that recycled ones may not have init_flag zeroed.
	  I couldn't even find anything that guarantees it is zeroed when
	  when the task structure is initially allocated.  In any case
	  I now initialize the entire FPE state in the thread structure to
	  zero when allocated and recycled.  See alloc_task_struct() and
	  flush_thread() in arch/arm/process.c.  The change to
	  alloc_task_struct() may not be necessary, but I left it in for
	  completeness (better safe than sorry).

Annotation

Implementation Notes