From: Sascha Hauer <s.hauer@pengutronix.de>
To: Antony Pavlov <antonynpavlov@gmail.com>
Cc: Peter Mamonov <piton@cs.niisi.ras.ru>, barebox@lists.infradead.org
Subject: Re: memcpy strange behaviour
Date: Wed, 4 Nov 2015 09:36:09 +0100 [thread overview]
Message-ID: <20151104083609.GJ25416@pengutronix.de> (raw)
In-Reply-To: <20151104110433.696aef0a00e53bb950e97674@gmail.com>
On Wed, Nov 04, 2015 at 11:04:33AM +0300, Antony Pavlov wrote:
> Hi!
>
> Peter has reported on strange barebox memcpy command behaviour on his MIPS board:
>
> he copies a file to memory using memcpy and then copyies appropriate memory contents
> back to another file. Next he checks files md5sum and the sums are differ.
>
> I have reproduced the problem on Qemu VersatilePB ARM board.
>
> Here is an instruction.
>
> Configure barebox:
>
> $ cd barebox.git
> $ export ARCH=arm
> $ export CROSS_COMPILE=<your cross compiler prefix>
> $ make versatilepb_defconfig
> $ sed -i "s/^# CONFIG_CMD_MD5SUM.*$/CONFIG_CMD_MD5SUM=y/" .config
>
> Prepare testfile on host and compile:
>
> $ dd if=/dev/zero bs=1 count=4414 | tr "\000" "\377" > defaultenv/defaultenv-2-base/testfile
> $ make
> ...
>
> Run barebox under qemu:
>
> $ qemu-system-arm -M versatilepb -nographic -monitor null -kernel arch/arm/pbl/zbarebox -serial stdio
> ...
> barebox# memcpy -s /env/testfile 0 0x01000000
>
> barebox# memcpy -d _testfile 0x01000000 0 4414
>
> barebox# md5sum /env/testfile _testfile
> bf8278051ba8de868def083bcc209002 /env/testfile 0x00000000 ... 0xffffffffffffffff
> e295c2bfe32498e03531017443120e89 _testfile 0x00000000 ... 0xffffffffffffffff
>
> barebox# memcmp -s /env/testfile -d _testfile 0 0
> files differ at offset 4408
>
> barebox# md -s /env/testfile 4400
> 00001130: ffffffff ffffffff ffffffff ffffffff ..............
>
> barebox# md -s _testfile 4400
> 00001130: ffffffff ffffffff 00000000 ffff0000 ..............
>
> barebox# md -b 0x01001130+0xe
> 01001130: ff ff ff ff ff ff ff ff 00 00 00 00 00 00 ..............
>
> barebox# md -b -s /env/testfile 0x1130+0xe
> 00001130: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ..............
>
> So you see that last 6 bytes have not been copied.
>
> Please comment this report!
This is fixed by:
http://www.spinics.net/lists/u-boot-v2/msg24850.html
Which I forgot to apply, but did now. The problem is that the newly
introduced O_RWSIZE_8 flag clashed with the O_CREAT flag. This means
that when a file is created (it's always set in memcpy) then we also do
8byte reads/writes which of course leads to the last bytes missing when
the length is not 8byte aligned. Fixed in current master.
Sascha
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox
prev parent reply other threads:[~2015-11-04 8:36 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-04 8:04 Antony Pavlov
2015-11-04 8:36 ` Sascha Hauer [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20151104083609.GJ25416@pengutronix.de \
--to=s.hauer@pengutronix.de \
--cc=antonynpavlov@gmail.com \
--cc=barebox@lists.infradead.org \
--cc=piton@cs.niisi.ras.ru \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox