On Fri, Apr 05, 2013 at 01:16:36PM -0500, Rob Herring wrote: > On 04/05/2013 12:13 PM, Wolfgang Denk wrote: > > Dear Rob, > > > > In message <515efe6f.1020...@gmail.com> you wrote: > >> > >>> In addition to commit 60d7d5a "env: fix potential stack overflow in > >>> environment functions" discussed here, I think we should also revert > >>> commit fcfa696 "ARM: increase lmb stack space reservation to 4KB" > >>> because it is conceptually broken and just papers over the real > >>> problems. > >> > >> Doing so will randomly break any system with a large command or print > >> buffer. For extra fun, it is dependent on the initrd or dtb image size > >> in terms of remainder of 4KB multiple. > > > > Well, yes, but that's because the LMB code makes unjustified > > assumptions about the memory usage, so it needs to be fixed there. > > > >> It is exactly the same code as PPC. It you look at the git history, PPC > >> made exactly the same change (1 to 4KB increase) around the same time > >> all the FDT boot code got copied from PPC to ARM. So ARM missed this > >> change. > > > > Thanks for pointing out. This adds commit 3882d7a "ppc: unused memory > > region too close to current stack pointer" to the list of patches that > > should bne reverted. > > > >> If the stack is all of RAM, then what address should the initrd and dtb > >> be copied to? > > > > Why do they have to be copied at all? Why cannot they remain where > > they have been loaded in the firtst place? The memcpy just costs time, > > which is a precious resource. Leave it to the user to find a > > reasonable location in RAM where he loads the data, and don't mess > > with it. > > I've got no freaking idea! I do turn that crap off in my environment > with initrd_high=0xffffffff. But the default operation is to copy it.
There's also fdt_high=0xffffffff which a number of platforms do to keep from FDT being thrown into highmem and unavailable to Linux. So, I shall revert the first commit in question today. For after v2013.04 we should: - Revert the other two commits Wolfgang found - See if there looks to be a real good reason for defaulting to relocating initrd/fdt, specifically up into the top of memory where we also know that U-Boot has / is alive and kicking. -- Tom
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