Messages in this thread | | | From | Caizhiyong <> | Subject | RE: [PATCH] block: add command line partition parser | Date | Thu, 15 Aug 2013 06:16:04 +0000 |
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> -----Original Message----- > From: Brian Norris [mailto:computersforpeace@gmail.com] > Sent: Thursday, August 15, 2013 1:00 PM > To: Caizhiyong > Cc: Andrew Morton; Karel Zak; linux-mtd@lists.infradead.org; > linux-kernel@vger.kernel.org; Wanglin (Albert); Artem Bityutskiy; Shmulik Ladkani; > Huang Shijie > Subject: Re: [PATCH] block: add command line partition parser > > On Thu, Aug 15, 2013 at 03:38:47AM +0000, Caizhiyong wrote: > > > -----Original Message----- > > > From: Brian Norris [mailto:computersforpeace@gmail.com] > > > Sent: Thursday, August 15, 2013 8:12 AM > > > To: Andrew Morton > > > Cc: Caizhiyong; Karel Zak; linux-mtd@lists.infradead.org; > > > linux-kernel@vger.kernel.org; Wanglin (Albert); Artem Bityutskiy; Shmulik > Ladkani; > > > Huang Shijie > > > Subject: Re: [PATCH] block: add command line partition parser > > > > > > On Wed, Aug 14, 2013 at 3:57 PM, Andrew Morton > > > <akpm@linux-foundation.org> wrote: > > > > On Tue, 13 Aug 2013 06:02:17 +0000 Caizhiyong <caizhiyong@huawei.com> wrote: > > > > > > > >> move the command line parser to a separate module, and change it into > > > >> library-style code. > > > >> > > > >> reference: https://lkml.org/lkml/2013/8/6/550 > > > > > > The most recent patch is an addendum to this linked patch then? > > > > > > > Well OK. But to prove the library's usefulness and to generally clean > > > > up the kernel, someone needs to sign up to the task of converting > > > > drivers/mtd/cmdlinepart.c to use this code. > > > > > > > > I've been hopefully cc'ing various MTD people but am not being > > > > overwhelmed with waves of enthusiasm ;) > > > > > > "I've been" implies that you have done so prior to this email. And > > > "people" implies more than one person. I see that you CC'd David > > > Woodhouse over a week ago, but he's fairly silent these days on MTD > > > things. It's Artem or me who handle most of the day-to-day of MTD. And > > > this is the first time I've seen this! (BTW, please include > > > linux-mtd@lists.infradead.org for anything involving MTD.) > > > > > > This seems reasonable, and I'd be willing to work with this proposal. > > > > > > Caizhiyong, can you submit a clear single patch (or series of > > > patches), CC'd to linux-mtd at least? Then we can see about supporting > > > it in MTD. It doesn't look too difficult, but I need to check that it > > > faithfully mimics the capability we currently rely on. There have been > > > previous discussions on changing it, but this was rejected in favor of > > > allowing more flexibility. Here's part of one such conversation: > > > > > > http://lists.infradead.org/pipermail/linux-mtd/2012-August/043599.html > > > http://lists.infradead.org/pipermail/linux-mtd/2012-September/043825.html > > > http://lists.infradead.org/pipermail/linux-mtd/2012-December/045322.html > > > > > > So I would recommend: > > > (1) consider carefully the implications of your command-line format > > > now, rather than later > > > (2) if you want MTD to use it, it needs to support the features we use now > > > > It is fully functional reference MTD, :-). > > I realize that. I just want to be clear that we have to reconcile (1) > and (2). IOW, if block device requirements stray too far from MTD > requirements, then we might as well drop the idea of integration now. > But if they agree, then we can move forward. > > > > Some particular cases to consider: overlapping partitions (how do > > > block devices handle overlapping partitions?), out-of-order > > > specification, zero sized partitions, mixed syntax (some specified > > > with an offset, some not), multiple '-' partitions. > > > > I think the 'offset' just is used to hide some MTD space. > > No, it specifies offset as a distance from the beginning of the flash, > so partitions can be numbered out of order. This is intentionally > utilized by some users, for example, to ensure that a particular > partition is always /dev/mtd0, even if it is not the first partition > physically. > > > There are two way: > > 1) redefine the 'offset' as a gap between forward partition and next partition. > > 2) add code forbid command line partitions overlapping and out-of-order. > > > > I recommend 1), it seems to solve those problem(overlapping and out-of-order), > but it will affect habit. > > The linked discussion is where MTD settled on retaining old practice. I > brought it up not so that we change it here, but so that you would > understand what you are agreeing to if you adopt a common MTD and block > device parsing infrastructure. > > [Note that I am much less familiar with block device mechanics than with > MTD.] Are any of the problem areas I mentioned actually forbidden on > block devices? I know, for instance, that an MBR partition table can > specify partitions out of order. And I've googled around and seen some > posts about people (unintentionally) ending up with overlapping hard > disk partitions. > > So from my primitive knowledge, it sounds like a block devices parser > could agree with the same principle put forward by Shmulik in that > second URL: > > "So far, mtdparts commandline parsing has been very lenient and liberal. > I think we should keep this approach; give the user the flexibility, > he'll be responsible to provide meaningful cmdline parts for his > system." > > Brian
I want to use the MTD command line partition method on block devices (eMMC). It is very suitable for embedded systems. I think, in embedded system partition method, if somebody need some feature on MTD device, he may be also need it on block device. so I fully functional reference MTD command line partition.
I tested the out-of-order and overlapping on my system, used command line partition, It is work ok. The block device code is not make any restrictions on partition out-of-order and overlapping.
I hope extend the flexibility to block device.
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