Messages in this thread | | | Date | Wed, 01 Aug 2012 08:56:14 +0100 | From | Lee Jones <> | Subject | Re: [PATCH 5/6] ARM: ux500: Enable HIGHMEM on all mop500 platforms |
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On 31/07/12 23:01, Russell King - ARM Linux wrote: > On Tue, Jul 31, 2012 at 08:50:02PM +0000, Arnd Bergmann wrote: >> On Tuesday 31 July 2012, Russell King - ARM Linux wrote: >>> I still fail to see how not having highmem enabled would ever cause memory >>> corruption errors (unless something dealing with memory in a very very >>> wrong way - iow, not using one of the reservation or memory allocation >>> methods provided by the kernel.) >> >> The problem is that all users of ux500 systems pass a command line like >> >> vmalloc=256M mem=128M@0 mali.mali_mem=32M@128M hwmem=168M@160M mem=48M@328M mem_issw=1M@383M mem=640M@384M >> >> This is of course totally bogus and should not be done. If I understand >> Lee correctly, one of the issues resulting from passing a command >> line like this without enabling highmem is memory corruption. > > But the question is _why_ does that corruption happen. > > From the above, we will end up with the kernel getting: > > 0x00000000 - 0x07ffffff (128M @ 0) > 0x14800000 - 0x177fffff (48M @ 328M) > 0x18000000 - 0x3fffffff (640M @ 384M) > > with: > > 0x08000000 - 0x081fffff used for mali > 0x0a000000 - 0x147fffff used for hwmem > 0x17f00000 - 0x17ffffff used for mem_issw > > Now, with highmem disabled, the kernel should still map exactly the > regions: 0x00000000 - 0x07ffffff, 0x14800000 - 0x177fffff, into the > direct mapped region, and truncate the 0x18000000 - 0x3fffffff > region appropriately, reducing the amount of memory available such > that it won't overlap the vmalloc area (which you've specified to be > a minimum of 256M.) > > This should _NOT_ cause any memory corruption. > > So, come on guys. Debugging is *mandatory* for this kind of problem. > Papering over it is obscene.
Actually I didn't go any further with it, as I changed to another identical piece of hardware and couldn't reproduce the issue.
FYI, here's the boot log from the broken board:
http://paste.ubuntu.com/1102017/
-- Lee Jones Linaro ST-Ericsson Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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