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Date: Wed, 20 Apr 2011 12:57:55 +0200 From: Pavel Machek <pavel@....cz> To: Alexander Holler <holler@...oftware.de> Cc: linux-kernel@...r.kernel.org Subject: Re: [PATCH 1/1] Implement /dev/byte (a generic byte source similiar to /dev/zero) On Mon 2011-04-18 13:37:56, Alexander Holler wrote: > This device outputs by default 0xff instead 0 which makes more sense > than 0 to clear e.g. FLASH based devices. Well, now you should provide example where you mmap /dev/byte, then write() the flash directly from the mapping. ... hmm, that brings good question: what happens on existing mappings when the byte is changed? > To make the device more general usable, the value it outputs is changeable > on a per file descriptor basis through simple writes to it. > Values can be decimal (0 - 255), octal (00 - 0377) or hex (0x0 - 0xff). > For other values (or strings) written to it, the write operation returns an > error and the subsequent output is undefined. ... > # Create a file of size 10GB and filled with 0xaa. > exec 5<>/dev/byte # Open /dev/byte and assign fd 5 to it > echo 0xaa >&5 # Instruct the device to output 0xaa That's seriously strange. /dev/byte should be changeable... by writing bytes. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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