From mboxrd@z Thu Jan 1 00:00:00 1970 From: pullip.cho@samsung.com (Cho KyongHo) Date: Fri, 21 Dec 2012 09:56:57 +0900 Subject: [PATCH] ARM: dts: fix split memory bank for SSDK5440 In-Reply-To: References: <1356030217-5472-1-git-send-email-kgene.kim@samsung.com> <1464138.NEt7mMkYJc@flatron> <20121220234146.GF14363@n2100.arm.linux.org.uk> <01f801cddf12$9f95c350$dec149f0$@samsung.com> Message-ID: <000a01cddf16$13a027b0$3ae07710$%cho@samsung.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org > From: Olof Johansson [mailto:olof at lixom.net] > Sent: Friday, December 21, 2012 9:36 AM > > On Thu, Dec 20, 2012 at 4:32 PM, Kukjin Kim wrote: > > Russell King - ARM Linux wrote: > >> > > > > [...] > > > >> > > >> > > What's the actual bug caused by this? The description is vague. > >> > > >> > The kernel panics early on NULL pointer dereference in memory > >> > initialization. > >> > > > > (Cc'ed KyongHo Cho) > > > > Yeah, correct. The size of memory bank should be under section size and > > current section size is 256MiB on EXYNOS. So if we don't change the section > > size, each memory bank should be under 256MiB. If not, as Tomasz said, > > kernel panic happens in mem_init(). > > That's a bug somewhere, the device tree should describe the hardware, > and not necessarily the massaged format that the kernel wants it in to > not trigger a bug. > > So I don't want to see this patch merged, I want to see a proper fix > instead, please. > > There are also already other exynos platforms and device trees with > more than 256MB in the memory node. Changing all of them this way > seems unreasonable. > As Kukjin said earlier, the kernel panic may happen while gathering memory statistics in mem_init()(arch/arm/mm/init.c). Russell King does not agreed to modify mem_init() instead he told that a memory bank must not cross section boundaries.