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From: "Michael S. Tsirkin" <mst@redhat.com>
To: qemu-devel@nongnu.org, zltjiangshi@gmail.com,
	Aurelien Jarno <aurelien@aurel32.net>
Subject: [Qemu-devel] bonito: PCI_STATUS questions
Date: Wed, 27 Oct 2010 18:12:28 +0200	[thread overview]
Message-ID: <20101027161227.GA9873@redhat.com> (raw)

I see code in bonito.c that clears bits:
PCI_STATUS_REC_MASTER_ABORT | PCI_STATUS_REC_TARGET_ABORT
on each read and write.

However
1. I don't see anything in code that would set these bits
2. The PCI spec says this about the status register:

	Reads to this register behave normally. Writes are slightly different in
	that bits can be reset, but not set. A one bit is reset (if it is not
	read-only) whenever the register is written, and the write data in the
	corresponding bit location is a 1. For instance, to clear bit 14 and not
	affect any other bits, write the value 0100_0000_0000_0000b to the
	register.

while the code in bonito.c resets the bits to 0 on each write.

Comments?

-- 
MST

             reply	other threads:[~2010-10-27 14:13 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-10-27 16:12 Michael S. Tsirkin [this message]
2010-10-28  0:57 ` [Qemu-devel] Re: bonito: PCI_STATUS questions chen huacai
2010-10-28  4:54   ` Michael S. Tsirkin
2010-10-28  8:31     ` chen huacai
2010-10-29  8:16       ` Michael S. Tsirkin
2010-10-29 13:34         ` chen huacai

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