From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from dell-paw-3.cambridge.redhat.com ([195.224.55.237] helo=passion.cambridge.redhat.com) by pentafluge.infradead.org with esmtp (Exim 3.22 #1 (Red Hat Linux)) id 18NrEB-0003Ml-00 for ; Mon, 16 Dec 2002 09:07:55 +0000 From: David Woodhouse In-Reply-To: <20021216092801.80539C6139@atlas.denx.de> References: <20021216092801.80539C6139@atlas.denx.de> To: Wolfgang Denk Cc: Paul Nash , "Linux-MTD (E-mail)" Subject: Re: Intel sez: Synchronous Flash and XIP is the future -- thoughts? Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Mon, 16 Dec 2002 09:38:34 +0000 Message-ID: <2466.1040031514@passion.cambridge.redhat.com> Sender: linux-mtd-admin@lists.infradead.org Errors-To: linux-mtd-admin@lists.infradead.org List-Help: List-Post: List-Subscribe: , List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: wd@denx.de said: > Also you might find problems running recent (and future) kernels in > XIP mode - the kernel text segment is often not exactly read-only. > Especially when you use one f the existing real-time extensions (but > not only then). It seems the amount of tweaking that is necessary for > XIP is growing with each new kernel release - to a level where it > becomes impractical. Also true. Of course we have to distinguish between XIP of file system pages and of the kernel -- I was ignoring the latter because it's even less sane than the former. If you ever want to write to the chip, you have to disable all interrupts and wait while the chip is busy. For up to 20 seconds, in the case of a slow erase. Of course, you could poll the interrupt controller while polling the flash for completion, and suspend the flash operation to service pending interrupts if they happen -- but that's really not the kind of thing that should be encouraged. Until people start making flash chips were every part of the chip other than the part which is being erased/written is readable during an erase or write operation, XIP is just a silly buzzword, for any writable application. -- dwmw2