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From: Hans Petter Selasky <hselasky@c2i.net>
To: freebsd-hackers@freebsd.org
Date: Mon, 26 Jan 2009 11:09:42 +0100
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Cc: Lukasz Jaroszewski <lvj@nietykalni.org>
Subject: Re: write(2) to /dev/ad4 = EINVAL
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On Monday 26 January 2009, Lukasz Jaroszewski wrote:
> Hi,
> after opening /dev/ad4 with success for O_RDWR, I am getting [EINVAL]
> from write(2), which according to man 2 write, means
>  ``     [EINVAL]           The pointer associated with d was
> negative.'', as you can see below it is not true, I have tried
> different block sizes, with same result.
>
> How can I write one byte to /dev/adN ?

Hi,

You cannot write one byte to /dev/adN, I think. Harddisks are block based. 
Please see:

diskinfo -v ad4

And especially the "sector size". When you seek and transfer data the offset 
and length must be a factor of the "sector size" or "block size". See also 
LBA, logical block address.

--HPS


>
>
> 1361 ow       CALL  open(0x80485e3,O_RDWR,<unused>0xbfbfecc8)
> 1361 ow       NAMI  "/dev/ad4"
>                        ;/dev/ad4 is DOS FAT formatted CF Card.
> 1361 ow       RET   open 3
>
> 1361 ow       CALL  write(0x3,0xbfbfecb8,0x8)
> 1361 ow       RET   write -1 errno 22 Invalid argument
>
> root@~(0) uname -r
> 7.0-STABLE
> -----------
> Best Regards
> Lukasz.
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