linux-kernel - RE: [PATCH 4/4] lib/hexdump.c: Allow multiple groups to be separated by lines '|'

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Message-ID: <051301d4ef83$34d2c710$9e785530$@d-silva.org>
Date:   Wed, 10 Apr 2019 19:52:58 +1000
From:   "Alastair D'Silva" <alastair@...ilva.org>
To:     "'David Laight'" <David.Laight@...LAB.COM>,
        "'Alastair D'Silva'" <alastair@....ibm.com>
Cc:     "'Jani Nikula'" <jani.nikula@...ux.intel.com>,
        "'Joonas Lahtinen'" <joonas.lahtinen@...ux.intel.com>,
        "'Rodrigo Vivi'" <rodrigo.vivi@...el.com>,
        "'David Airlie'" <airlied@...ux.ie>,
        "'Daniel Vetter'" <daniel@...ll.ch>,
        "'Karsten Keil'" <isdn@...ux-pingi.de>,
        "'Jassi Brar'" <jassisinghbrar@...il.com>,
        "'Tom Lendacky'" <thomas.lendacky@....com>,
        "'David S. Miller'" <davem@...emloft.net>,
        "'Jose Abreu'" <Jose.Abreu@...opsys.com>,
        "'Kalle Valo'" <kvalo@...eaurora.org>,
        "'Stanislaw Gruszka'" <sgruszka@...hat.com>,
        "'Benson Leung'" <bleung@...omium.org>,
        "'Enric Balletbo i Serra'" <enric.balletbo@...labora.com>,
        "'James E.J. Bottomley'" <jejb@...ux.ibm.com>,
        "'Martin K. Petersen'" <martin.petersen@...cle.com>,
        "'Greg Kroah-Hartman'" <gregkh@...uxfoundation.org>,
        "'Alexander Viro'" <viro@...iv.linux.org.uk>,
        "'Petr Mladek'" <pmladek@...e.com>,
        "'Sergey Senozhatsky'" <sergey.senozhatsky@...il.com>,
        "'Steven Rostedt'" <rostedt@...dmis.org>,
        "'Andrew Morton'" <akpm@...ux-foundation.org>,
        <intel-gfx@...ts.freedesktop.org>,
        <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
        <netdev@...r.kernel.org>, <ath10k@...ts.infradead.org>,
        <linux-wireless@...r.kernel.org>, <linux-scsi@...r.kernel.org>,
        <linux-fbdev@...r.kernel.org>, <devel@...verdev.osuosl.org>,
        <linux-fsdevel@...r.kernel.org>
Subject: RE: [PATCH 4/4] lib/hexdump.c: Allow multiple groups to be separated by lines '|'

> -----Original Message-----
> From: David Laight <David.Laight@...LAB.COM>
> Sent: Wednesday, 10 April 2019 6:45 PM
> To: 'Alastair D'Silva' <alastair@....ibm.com>; alastair@...ilva.org
> Cc: Jani Nikula <jani.nikula@...ux.intel.com>; Joonas Lahtinen
> <joonas.lahtinen@...ux.intel.com>; Rodrigo Vivi <rodrigo.vivi@...el.com>;
> David Airlie <airlied@...ux.ie>; Daniel Vetter <daniel@...ll.ch>; Karsten Keil
> <isdn@...ux-pingi.de>; Jassi Brar <jassisinghbrar@...il.com>; Tom Lendacky
> <thomas.lendacky@....com>; David S. Miller <davem@...emloft.net>;
> Jose Abreu <Jose.Abreu@...opsys.com>; Kalle Valo
> <kvalo@...eaurora.org>; Stanislaw Gruszka <sgruszka@...hat.com>;
> Benson Leung <bleung@...omium.org>; Enric Balletbo i Serra
> <enric.balletbo@...labora.com>; James E.J. Bottomley
> <jejb@...ux.ibm.com>; Martin K. Petersen <martin.petersen@...cle.com>;
> Greg Kroah-Hartman <gregkh@...uxfoundation.org>; Alexander Viro
> <viro@...iv.linux.org.uk>; Petr Mladek <pmladek@...e.com>; Sergey
> Senozhatsky <sergey.senozhatsky@...il.com>; Steven Rostedt
> <rostedt@...dmis.org>; Andrew Morton <akpm@...ux-foundation.org>;
> intel-gfx@...ts.freedesktop.org; dri-devel@...ts.freedesktop.org; linux-
> kernel@...r.kernel.org; netdev@...r.kernel.org;
> ath10k@...ts.infradead.org; linux-wireless@...r.kernel.org; linux-
> scsi@...r.kernel.org; linux-fbdev@...r.kernel.org;
> devel@...verdev.osuosl.org; linux-fsdevel@...r.kernel.org
> Subject: RE: [PATCH 4/4] lib/hexdump.c: Allow multiple groups to be
> separated by lines '|'
> 
> From: Alastair D'Silva
> > Sent: 10 April 2019 04:17
> > With the wider display format, it can become hard to identify how many
> > bytes into the line you are looking at.
> >
> > The patch adds new flags to hex_dump_to_buffer() and
> print_hex_dump()
> > to print vertical lines to separate every N groups of bytes.
> >
> > eg.
> > buf:00000000: 454d414e 43415053|4e495f45 00584544
> NAMESPAC|E_INDEX.
> > buf:00000010: 00000000 00000002|00000000 00000000  ........|........
> 
> Ugg, that is just horrid.
> It is enough to add an extra space if you really need the columns to be more
> easily counted.
>

I did consider that, but it would be a more invasive change, as the buffer length required would differ based on the flags.
 
> I'm not even sure that is needed if you are printing 32bit words.
> OTOH 32bit words makes 64bit values really stupid on LE systems.
> Bytes with extra spaces every 4 bytes is the format I prefer even for long
> lines.
> 
> Oh, and if you are using hexdump() a lot you want a version that never uses
> snprintf().
> 
> 	David
> 
> -
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> 
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