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 > >
