On 10 August 2012 19:53, Steven <wangwangk...@gmail.com> wrote: > On Fri, Aug 10, 2012 at 11:47 AM, Peter Maydell > <peter.mayd...@linaro.org> wrote: >> On 10 August 2012 03:11, Steven <wangwangk...@gmail.com> wrote: >>> The function definition has a return address type tb_page_addr_t. >>> tb_page_addr_t get_page_addr_code(CPUArchState *env1, target_ulong addr) >>> >>> I am wondering is this address the guest physical address or the host >>> virtual address. >> >> In linux-user mode the returned address is the guest virtual address. >> In system mode it is a ram_addr_t. (the comment above the implementation >> says "the returned address is not exactly the physical address: it >> is the offset relative to phys_ram_base" but this is out of date I think). >> A ram_addr_t is neither a host address nor a guest physical address >> but it's closely related to a guest physaddr (you can think of it as >> if all the RAM in the system was put into a straight line and then the > > My question is related to system mode. > Is the RAM you mean the guest physical address, which is a continuous > sequence of numbers beginning from 0 to the max of allocated RAM of > the guest? > >> ram_addr_t is an index into that). > > If the returned value of get_page_addr_code is the index to that > straight line, I am wondering if it is the guest physical address.
No, it is definitely not the guest physical address. Consider the case where there are two aliases of the same RAM in guest physical memory -- two physical addresses might map to a single ram_addr_t. Consider the case where there is a 'hole' in memory -- ram_addr_t and physical address are not identical there either. > So if I want to get the guest physical address (GPA) of a > tb_page_addr_t, can I do > tb_page_addr_t = returned value from get_page_addr_code + phys_ram_base > Is this translation correct? This is wrong on several counts: (a) there's no such thing as phys_ram_base any more (it was removed several years ago) and (b) there is no single unique guest physical address corresponding to a tb_page_addr_t, so what you are trying to do is not well defined. What are you trying to do anyway and why do you want to call get_page_addr_code() ? -- PMM
