The value loaded into r0 in copy_and_flush() represents the number of 8-byte words processed between cache synchronization operations.
The existing comment refers to cache line size, which can make it appear that the value is a cache line size in bytes rather than a loop count. Clarify the comment to explain that the loop processes 8 words (64 bytes) per cache synchronization iteration, and that increasing the value would skip cache maintenance for intermediate cache lines. This is a comment-only change with no functional impact. Signed-off-by: Nikhil Kumar Singh <[email protected]> --- arch/powerpc/kernel/head_64.S | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S index 63432a33ec49..e21c2bce8f7e 100644 --- a/arch/powerpc/kernel/head_64.S +++ b/arch/powerpc/kernel/head_64.S @@ -713,14 +713,14 @@ p_end: .8byte _end - copy_to_here _GLOBAL(copy_and_flush) addi r5,r5,-8 addi r6,r6,-8 -4: li r0,8 /* Use the smallest common */ - /* denominator cache line */ - /* size. This results in */ - /* extra cache line flushes */ - /* but operation is correct. */ - /* Can't get cache line size */ - /* from NACA as it is being */ - /* moved too. */ +4: li r0,8 /* r0 is the number of 8-byte words */ + /* to copy per cache sync iteration. */ + /* 8 words * 8 bytes = 64 bytes. 64B is */ + /* the current default cache line size. */ + /* This is a loop count, not a byte */ + /* count. Increasing it will skip */ + /* dcbst/icbi for lines in between and */ + /* leave stale instructions in icache. */ mtctr r0 /* put # words/line in ctr */ 3: addi r6,r6,8 /* copy a cache line */ -- 2.43.5
