On Wed, May 26, 2010 at 2:27 PM, Mayank Kaushik <[email protected]>wrote:
> On Wed, May 26, 2010 at 1:14 PM, Joel Fernandes <[email protected]>wrote: > >> Hi Mayank, >> >> > To support my kernel debugging tool, I need to examine memory at >> specific >> > locations in the physical address space of a CPU. >> > Obviously, I need to map these physical addresses into the VA space of >> the >> > CPU. And this has to be done in an interrupt context, when the kernel >> > debugger will have broken into the kernel. >> >> That is exactly what kmap and kmap_atomic are used for. Did you try using >> these? >> >> Joel's suggestion works for i386. I can map a page at the specific address using the kind of protection I want using kmap_atomic_prot(). On x86_64, this isn't present, presumably because all of the physical memory is mapped at PAGE_OFFSET, so can be accessed at __va(phys_addr). However, what if the physical address I want to map is device memory that should be uncached? -- kthxbye -Mayank
