> -----Original Message----- > From: Brian Norris [mailto:computersforpe...@gmail.com] > Sent: Thursday, August 15, 2013 3:10 PM > To: Caizhiyong > Cc: Andrew Morton; Karel Zak; linux-...@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 06:16:04AM +0000, Caizhiyong wrote: > > > -----Original Message----- > > > From: Brian Norris [mailto:computersforpe...@gmail.com] > > > Sent: Thursday, August 15, 2013 1:00 PM > > > To: Caizhiyong > > > Cc: Andrew Morton; Karel Zak; linux-...@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:computersforpe...@gmail.com] > > > > > Sent: Thursday, August 15, 2013 8:12 AM > > > > > To: Andrew Morton > > > > > Cc: Caizhiyong; Karel Zak; linux-...@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 > > > > > <a...@linux-foundation.org> wrote: > > > > > > On Tue, 13 Aug 2013 06:02:17 +0000 Caizhiyong > > > > > > <caizhiy...@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-...@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 agree. > > I'm curious: have you seen any need for a similar arrangement via > device-tree? See, for example, drivers/mtd/ofpart.c.
So far, I have no seen. We mainly use ARM. For ARM, device-tree is a new thing. > > > 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. > > OK, good. Thanks for checking. > > > I hope extend the flexibility to block device. > > Sure. I'll try to review the full patch soon and test out integrating > it with MTD. If there is no problem, I will send my next patch, mtd cmdline parts use cmdline-parser lib. > > Thanks, > Brian -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/