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On 11/28/06, Dave Airlie <airlied@gmail.com> wrote: > On 11/28/06, Jon Ringle <jringle@vertical.com> wrote: <snip> > > It looks promising, however, I need to reserve a physical address area > > that is well known (so that the code running on the other processor > > knows where in PCI memory to write to). It appears that > > dma_alloc_coherent returns the address that it allocated. Instead I need > > something where I can tell it what physical address and range I want to use. > >>> I've seen other projects just boot a 128M board with mem=120M and just > use the 8MB at 120 to talk to the other processor.. > Yes, this can be used if required physical-memory exists in the last part of RAM as if you use mem=<xxxM> then kernel will only use memory less than or equal-to <xxxM> and above can be used by drivers (or any kernel module) might be through ioremap which takes physical-address. But if lets say we need only 1MB portion of specific physical-memory region then AFAIK it must be done by hacking in kernel code during memory-initialization (mem_init function) where it is marking/checking pages as/are reserved; you can simply mark you required pages as reserved too and set their count to some-value if you want to know later which pages are reserved by you. (can do this reservation work here: http://lxr.free-electrons.com/source/arch/i386/mm/init.c#605). CMIIW -- Fawad Lateef - 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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