On Mon, Jul 06, 2015 at 04:05:46PM -0700, Peter Crosthwaite wrote: > On Mon, Jul 6, 2015 at 3:49 PM, Peter Maydell <peter.mayd...@linaro.org> > wrote: > > On 6 July 2015 at 23:42, Peter Crosthwaite <peter.crosthwa...@xilinx.com> > > wrote: > >> On Mon, Jul 6, 2015 at 3:29 PM, Peter Maydell <peter.mayd...@linaro.org> > >> wrote: > >>> On 6 July 2015 at 19:53, <mead...@codesourcery.com> wrote: > >>>> From: Meador Inge <mead...@codesourcery.com> > >>>> > >>>> This patch series opens up the "any" CPU for system-mode and > >>>> adds a new "any" variant named "anyvfp" that initializes the > >>>> FP coprocessors as well. > >>> > >>> We deliberately removed cpu "any" for system mode in > >>> commit f5f6d38b7458b8a back in 2013; I think the rationale > >>> for its removal still holds. If you're emulating a system > >>> you're emulating a specific system and you get a real > >>> CPU. A CPU with no impdef sysregs or initialized feature > >>> and ID registers is broken... > >> > >> You can still have a CPU+RAM only machine model, load elfs and get > >> meaningful result on a debugger. > > > > Yeah, but what does "any" get you over just going ahead > > and specifying your CPU type? What interrupt controller > > should the "any" CPU type have? Generic timers? Etc. > > > > None and none. You are only interested in CPU internal state with no IO at > all.
Exactly. We have a use-case where QEMU acts as basically an ISS and we only care about architecture level support. So, someone compiles their application with various options (-march=armv7-a, -march=arv5te, etc...) and runs those through GDB that connects to the QEMU GDB stub. From the QEMU side we can launch an instance with '-cpu any' and expect most applications to run on it regardless of how it was built with GCC. This is a reasonable use-case and it is a very small change to QEMU, which introduces hardly any complexity or maintenance burden. > > There isn't zero utility there, but I don't really think > > there's enough to justify cluttering up QEMU with when > > "-cpu cortex-a15" is not very much more to type, and > > has the advantage of being something that actually > > exists in reality. As mentioned above, there is utility and saying that it is "clutter" is a bit of an exaggeration (it is 5 deletions(-) that introduces *one* new option). > > There is a clean definition of an ARM CPU without any IO however which > has utility in compiler testing. I agree. -- Meador
