On 2026/07/09 11:40 AM, Nikhil Kumar Singh wrote: > Hi Mukesh, > > Ideally, checkpatch should take care of this, I see no checkpatch errors.
That is because the default $max_line_length is set to 100 columns in checkpatch.pl scripts. The kernel coding style document recommends 80, but checkpatch enforces 100 unless you pass --max-line-length=80 explicitly. my $max_line_length = 100; You will see the warnings being reported when you run the script as: ❯ scripts/checkpatch.pl ./v2_20260706_nikhilks_powerpc_64s_clarify_copy_and_flush_cache_sync_loop_comment.mbx --max-line-length=80 WARNING: line length of 82 exceeds 80 columns #44: FILE: arch/powerpc/kernel/head_64.S:716: +4: li r0,8 /* r0 is the number of 8-byte words */ [...] total: 0 errors, 12 warnings, 26 lines checked I agree with Mukesh here and I think the comment should be fixed to fit within 80 column width limit as staying within 80 columns is certainly still preferred. Thanks, Amit > > ``` > ./scripts/checkpatch.pl > v2-0001-powerpc-64s-Clarify-copy_and_flush-cache-sync-loo.patch > total: 0 errors, 0 warnings, 26 lines checked > > v2-0001-powerpc-64s-Clarify-copy_and_flush-cache-sync-loo.patch has no > obvious style problems and is ready for submission. > ``` > > Thanks > ~ Nikhil > > On 07/07/26 12:48, Nikhil Kumar Singh wrote: > > Hi Mukesh, > > > > Thanks for reviewing the patch and for the suggestion. > > I'd prefer to keep the current alignment as I find it a bit more > > readable. > > > > Thanks, > > ~ Nikhil > > > > On 07/07/26 11:08, Mukesh Kumar Chaurasiya wrote: > > > On Mon, Jul 06, 2026 at 01:57:08PM +0530, Nikhil Kumar Singh wrote: > > > > 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 | 20 ++++++++++++-------- > > > > 1 file changed, 12 insertions(+), 8 deletions(-) > > > > > > > > diff --git a/arch/powerpc/kernel/head_64.S > > > > b/arch/powerpc/kernel/head_64.S > > > > index 63432a33ec49..a54f6f979173 100644 > > > > --- a/arch/powerpc/kernel/head_64.S > > > > +++ b/arch/powerpc/kernel/head_64.S > > > > @@ -713,14 +713,18 @@ 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 may skip */ > > > > + /* dcbst/icbi for lines in between and */ > > > > + /* leave stale instructions in icache. */ > > > > + /* 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. */ > > > The comment looks fine. But the alignement of the comment is still > > > different from earlier. Keep the alignment same as earlier, it looks a > > > little nicer. > > > > > > Regards, > > > Mukesh > > > > mtctr r0 /* put # words/line in ctr */ > > > > 3: addi r6,r6,8 /* copy a cache line */ > > > > -- > > > > 2.43.5 > > > >
