Hmm, I think there is an expectation that virt->phys is a simple translation (ie, subtract KERNELBASE) for lowmem. lowmem most parts tops out at 768M. So changing VMALLOC_START would break that.
Is there an issue with moving the IMMR virt address up higher? - kumar On Mar 8, 2005, at 3:16 PM, Rune Torgersen wrote: > What about moving the VMALLOC_START and VMALLOC_END #defines to > something else (like start at 0x80000000 and end at 0xc0000000), or > will > that break some assumptions in the kernel about the position of the > vmalloc area? > > > -----Original Message----- > > From: Matt Porter [mailto:mporter at kernel.crashing.org] > > Sent: Tuesday, March 08, 2005 14:33 > > To: Rune Torgersen > > Cc: Kumar Gala; linuxppc-embedded at ozlabs.org > > Subject: Re: Lots of memory on 826x > > > > On Tue, Mar 08, 2005 at 12:37:33PM -0600, Rune Torgersen wrote: > > > Ok... Got a little closer.... > > > > > > I have PCI (outbound) mapped in the area 0x80000000-0x8fffffff > > > (prefetch/non-prefetch and IO) > > > IMMR of cource is at 0xf0000000 > > > > > > So I map the IO as following: > > > ??? /* Map IMMR region to a 256MB BAT */ > > > ??? addr = (cpm2_immr != NULL) ? (uint)cpm2_immr : CPM_MAP_ADDR; > > > ??? io_block_mapping(addr, addr, 0x10000000, _PAGE_IO); > > > > > > ??? io_block_mapping(0x80000000, 0x80000000, 0x10000000, _PAGE_IO); > > > > > > Now I can almost boot....: > > > It craches when trying to read from harddisk > > > (only happens with more than 512MB) > > > > That's expected if you are going to 768MB. You have kernel lowmem > > being mapped at 0xc0000000+<size_of_system_memory>. With 768MB that > > takes you all the way to where you have the IMMR mapped 1:1 I > > guess. This leaves no room for vmalloc space.? With 768MB of ram > > the kernel will calculate VMALLOC_START at 0xf1000000 which is a > > problem. > > > > A few options are: > > > > * Move the IMMR much higher to allow vmalloc space > > * Modify maximum low memory to limit to 512MB using the advanced > >?? options menu > > * Modify KERNELBASE to something like 0xa0000000 using the advanced > >?? options menu > > > > All of these methods will provide addition vmalloc space. > > > > Don't forget to turn on HIGHMEM to use everything above MAX_LOW_MEM. > > > > -Matt > > > >
