On Sat 2019-04-13 09:28:03, Alastair D'Silva wrote: > > -----Original Message----- > > From: Petr Mladek <[email protected]> > > Sent: Saturday, 13 April 2019 12:04 AM > > To: Alastair D'Silva <[email protected]> > > Cc: [email protected]; Jani Nikula <[email protected]>; > Joonas > > Lahtinen <[email protected]>; Rodrigo Vivi > > <[email protected]>; David Airlie <[email protected]>; Daniel Vetter > > <[email protected]>; Karsten Keil <[email protected]>; Jassi Brar > > <[email protected]>; Tom Lendacky <[email protected]>; > > David S. Miller <[email protected]>; Jose Abreu > > <[email protected]>; Kalle Valo <[email protected]>; > > Stanislaw Gruszka <[email protected]>; Benson Leung > > <[email protected]>; Enric Balletbo i Serra > > <[email protected]>; James E.J. Bottomley > > <[email protected]>; Martin K. Petersen <[email protected]>; > > Greg Kroah-Hartman <[email protected]>; Alexander Viro > > <[email protected]>; Sergey Senozhatsky > > <[email protected]>; Steven Rostedt <[email protected]>; > > Andrew Morton <[email protected]>; intel- > > [email protected]; [email protected]; linux- > > [email protected]; [email protected]; > > [email protected]; [email protected]; linux- > > [email protected]; [email protected]; > > [email protected]; [email protected] > > Subject: Re: [PATCH 2/4] lib/hexdump.c: Optionally suppress lines of > filler > > bytes > > > > On Wed 2019-04-10 13:17:18, Alastair D'Silva wrote: > > > From: Alastair D'Silva <[email protected]> > > > > > > Some buffers may only be partially filled with useful data, while the > > > rest is padded (typically with 0x00 or 0xff). > > > > > > This patch introduces flags which allow lines of padding bytes to be > > > suppressed, making the output easier to interpret: > > > HEXDUMP_SUPPRESS_0X00, HEXDUMP_SUPPRESS_0XFF > > > > > > The first and last lines are not suppressed by default, so the > > > function always outputs something. This behaviour can be further > > > controlled with the HEXDUMP_SUPPRESS_FIRST & > > HEXDUMP_SUPPRESS_LAST flags. > > > > > > An inline wrapper function is provided for backwards compatibility > > > with existing code, which maintains the original behaviour. > > > > > > > > diff --git a/lib/hexdump.c b/lib/hexdump.c index > > > b8a164814744..2f3bafb55a44 100644 > > > --- a/lib/hexdump.c > > > +++ b/lib/hexdump.c > > > +void print_hex_dump_ext(const char *level, const char *prefix_str, > > > + int prefix_type, int rowsize, int groupsize, > > > + const void *buf, size_t len, u64 flags) > > > { > > > const u8 *ptr = buf; > > > - int i, linelen, remaining = len; > > > + int i, remaining = len; > > > unsigned char linebuf[64 * 3 + 2 + 64 + 1]; > > > + bool first_line = true; > > > > > > if (rowsize != 16 && rowsize != 32 && rowsize != 64) > > > rowsize = 16; > > > > > > for (i = 0; i < len; i += rowsize) { > > > - linelen = min(remaining, rowsize); > > > + bool skip = false; > > > + int linelen = min(remaining, rowsize); > > > + > > > remaining -= rowsize; > > > > > > + if (flags & HEXDUMP_SUPPRESS_0X00) > > > + skip = buf_is_all(ptr + i, linelen, 0x00); > > > + > > > + if (!skip && (flags & HEXDUMP_SUPPRESS_0XFF)) > > > + skip = buf_is_all(ptr + i, linelen, 0xff); > > > + > > > + if (first_line && !(flags & HEXDUMP_SUPPRESS_FIRST)) > > > + skip = false; > > > + > > > + if (remaining <= 0 && !(flags & HEXDUMP_SUPPRESS_LAST)) > > > + skip = false; > > > + > > > + if (skip) > > > + continue; > > > > IMHO, quietly skipping lines could cause a lot of confusion, espcially > when the address is not printed. > > > It's up to the caller to decide how they want it displayed.
I wonder who would want to quietly skip some data values. Are you using it yourself? Could you please provide an example? I do not see why we would need to complicate the API and code by this. The behavior proposed by Tvrtko Ursulin makes much more sense. I mean https://lkml.kernel.org/r/[email protected] > > I wonder how it would look like when we print something like: > > > > --- skipped XX lines full of 0x00 --- > > This could be added as a later enhancement, with a new flag (eg. > HEXDUMP_SUPPRESS_VERBOSE). Who will add this later? Frankly, this looks like a half baked feature that it good enough for you. If you want it upstream, it must behave reasonably and it must be worth it. Best Regards, Petr
