On Thu, Aug 25, 2011 at 1:54 PM, Pekka Enberg <penberg@xxxxxxxxxx> wrote: > > On 8/25/11 8:34 AM, Asias He wrote: > > Hi, David > > On Thu, Aug 25, 2011 at 6:25 AM, David Evensky <evensky@xxxxxxxxxx> wrote: >> >> >> This patch adds a PCI device that provides PCI device memory to the >> guest. This memory in the guest exists as a shared memory segment in >> the host. This is similar memory sharing capability of Nahanni >> (ivshmem) available in QEMU. In this case, the shared memory segment >> is exposed as a PCI BAR only. >> >> A new command line argument is added as: >> --shmem pci:0xc8000000:16MB:handle=/newmem:create >> >> which will set the PCI BAR at 0xc8000000, the shared memory segment >> and the region pointed to by the BAR will be 16MB. On the host side >> the shm_open handle will be '/newmem', and the kvm tool will create >> the shared segment, set its size, and initialize it. If the size, >> handle, or create flag are absent, they will default to 16MB, >> handle=/kvm_shmem, and create will be false. > > I think it's better to use a default BAR address if user does not specify one as well. > This way, > > ./kvm --shmem > > will work with default values with zero configuration. > > Does that sort of thing make sense here? It's a special purpose device > and the guest is expected to ioremap() the memory so it needs to > know the BAR. I mean a default bar address for --shmem device. Yes, guest needs to know this address, but even if we specify the address at command line the guest still does not know this address, no? So having a default bar address does no harm. >> The address family, >> 'pci:' is also optional as it is the only address family currently >> supported. Only a single --shmem is supported at this time. > > So, let's drop the 'pci:' prefix. > > That means the user interface will change if someone adds new address > families. So we should keep the prefix, no? We can have a more flexible option format which does not depend on the order of args, e.g.: --shmem bar=0xc8000000,size=16MB,handle=/newmem,ops=create, type=pci if user does not specify sub-args, just use the default one. -- Asias He -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
