From mboxrd@z Thu Jan 1 00:00:00 1970 From: ben-linux@fluff.org (Ben Dooks) Date: Mon, 31 May 2010 01:39:11 +0100 Subject: [PATCH] s5pv210: Change the base ram address to 0x3000'0000 In-Reply-To: <20100528023559.GA8174@july> References: <20100528023559.GA8174@july> Message-ID: <20100531003911.GM7248@trinity.fluff.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, May 28, 2010 at 11:35:59AM +0900, Kyungmin Park wrote: > s5pc110 (aka s5pv210) has 2 DRAM port and used it both usually. > Assume DMC0 starts with 0x2000'0000 with 128MiB. > DMC1 starts with 0x4000'0000 with 128MiB. > Note that DMC1 has to start address 0x4000'0000 at least. > > Then there's too much memory hole 0x1800'0000 (128MiB + 256MiB) > > To reduce memory waste, the DMC0 start with 0x3000'0000. > > Signed-off-by: Kyungmin Park > --- > diff --git a/arch/arm/mach-s5pv210/Makefile.boot b/arch/arm/mach-s5pv210/Makefile.boot > index ff90aa1..b0909e3 100644 > --- a/arch/arm/mach-s5pv210/Makefile.boot > +++ b/arch/arm/mach-s5pv210/Makefile.boot > @@ -1,2 +1,2 @@ > - zreladdr-y := 0x20008000 > -params_phys-y := 0x20000100 > + zreladdr-y := 0x30008000 > +params_phys-y := 0x30000100 Apart from the technical comments that have been in this thread, I would like to share notes about making changes like these that affect the entire SoC kernel build. Firstly, changing this effects the rest of the users, not everyone is using the same device with same layout. This configuration boots on both S5PC110 and S5PV210 devices. Some of these _have_ to support 1GiB of memory. Some of them have their bootloaders programemd to start at 0x20... So please think of how this will affect everyone else. Secondly, if you have thought about point 1, then please let us know in the commit messages. The commit message isn't just a log of what the patch does, it can also be used to show any necessary working about what is happening and side-effects of it. Thirdly, the kernel's default configuration for a SoC/arch isn't meant to be the best-fit for your board(s) or development practicies. It is meant to cover as many devices as possible, to allow build testing and to have something that people can test with. If it is not the most efficient on the board, then make your own defconfig that is a best fit for your purposes. So, sometimes when this sort of change is required there may be a case of making it configurable so that your own defconfig/boardconfig can select it for your own projects. Please keep in mind that other people have/are using the kernel and that some changes have an affect on other projects as well as your own. This is why user-space facing changes are the most debated and difficult to do, kernel internals shift quite easily, whilst the data exported to userspace is kept as stable as possible. -- Ben Q: What's a light-year? A: One-third less calories than a regular year.