Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932428AbWBXTOt (ORCPT ); Fri, 24 Feb 2006 14:14:49 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932432AbWBXTOt (ORCPT ); Fri, 24 Feb 2006 14:14:49 -0500 Received: from mx3.mail.ru ([194.67.23.149]:2136 "EHLO mx3.mail.ru") by vger.kernel.org with ESMTP id S932428AbWBXTOt (ORCPT ); Fri, 24 Feb 2006 14:14:49 -0500 From: Andrey Borzenkov To: linux-kernel@vger.kernel.org Subject: "Ghost" devices in /sys/firmware/edd Date: Fri, 24 Feb 2006 22:14:34 +0300 User-Agent: KMail/1.9.1 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200602242214.46290.arvidjaar@mail.ru> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1745 Lines: 63 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 I have single drive hda; still EDD shows valid and the _same_ MBR signature for all possible 16 drives: {pts/0}% cat /sys/firmware/edd/*/mbr_* 0x7fca3a0a 0x7fca3a0a 0x7fca3a0a 0x7fca3a0a 0x7fca3a0a 0x7fca3a0a 0x7fca3a0a 0x7fca3a0a 0x7fca3a0a 0x7fca3a0a 0x7fca3a0a 0x7fca3a0a 0x7fca3a0a 0x7fca3a0a 0x7fca3a0a 0x7fca3a0a other attributes are correctly present for the drive 0x80 only. Not being expert in x86 assembly, but comparing main loops for signature and other info: signature: int $0x13 sti # work around buggy BIOSes popw %dx popw %es popw %bx jc edd_mbr_sig_done # on failure, we're done. extended EDD info: edd_check_ext: movb $CHECKEXTENSIONSPRESENT, %ah # Function 41 movw $EDDMAGIC1, %bx # magic int $0x13 # make the call jc edd_done # no more BIOS devices Is it possible that carry flag is cleared between return from int 0x13 and querying for it in the former case? This would perfectly explain that EDD does not notice failure of reading sector and simply copies the same signature from the very first drive. - -andrey -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2.1 (GNU/Linux) iD8DBQFD/1smR6LMutpd94wRAncjAJ0b9wLmKK9V2bc93ghAIUa7dY5VWQCfZ8BP aiT8y5TX3DE05ZN8wfnfg7E= =uB1I -----END PGP SIGNATURE----- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/