On 20.04.2010, at 13:33, Takuya Yoshikawa wrote: > (2010/04/20 20:15), Alexander Graf wrote: >> >> On 20.04.2010, at 13:03, Takuya Yoshikawa wrote: >> >>> We can now export the addree of the bitmap created by do_mmap() >>> to user space. For the sake of this, we introduce a new API: >>> >>> KVM_SWITCH_DIRTY_LOG: application can use this to trigger the >>> switch of the bitmaps and get the address of the bitmap which >>> has been used until now. This reduces the copy of the dirty >>> bitmap from the kernel. >>> >>> Signed-off-by: Takuya Yoshikawa<yoshikawa.takuya@xxxxxxxxxxxxx> >>> Cc: Fernando Luis Vazquez Cao<fernando@xxxxxxxxxxxxx> >>> --- >>> Documentation/kvm/api.txt | 23 +++++++++++++++++++++++ >>> arch/ia64/kvm/kvm-ia64.c | 19 ++++++++++++++----- >>> arch/powerpc/kvm/book3s.c | 19 ++++++++++++++----- >>> arch/x86/kvm/x86.c | 32 ++++++++++++++++++++++++++------ >>> include/linux/kvm.h | 6 ++++-- >>> include/linux/kvm_host.h | 7 ++++--- >>> virt/kvm/kvm_main.c | 41 ++++++++++++++++++++++++++++++++++++----- >>> 7 files changed, 121 insertions(+), 26 deletions(-) >>> >> >> [...] >> >>> diff --git a/include/linux/kvm.h b/include/linux/kvm.h >>> index 23ea022..9fa6f1e 100644 >>> --- a/include/linux/kvm.h >>> +++ b/include/linux/kvm.h >>> @@ -12,7 +12,7 @@ >>> #include<linux/ioctl.h> >>> #include<asm/kvm.h> >>> >>> -#define KVM_API_VERSION 12 >>> +#define KVM_API_VERSION 13 >> >> Is there a way to keep both interfaces around for some time at least? I'd prefer the API version not to change if not _really_ necessary. >> >> To enable the new dirty mapping you could for example use KVM_CAP_ENABLE_CAP :-). > > Thanks, I did not know what is the appropriate way for this kind of change. > > I just read the comments in the kvm.h and thought I had to update the number whenever > I added some entries to kvm.h . The rule of thumb is: KVM_API_VERSION change -> complete breakage. No way to run older userspace on newer kernels. new CAP -> optional feature If I read correctly you're changing quite a few existing interfaces, so old userspace wouldn't work anymore. Hence I'm proposing using activating the new way of dirty logging optionally. Alex -- 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
