On Tue, 3 Dec 2013 15:40:37 +0000 Julien Grall <julien.gr...@linaro.org> wrote:
> On ARM (32 bits and 64 bits), the double-word is 8-bytes aligned. This will > result on different structure from Xen and Linux repositories. > > As Linux is using __packed__ attribute, it must have a 4-bytes padding before > each "id" field. > > This change breaks guest block support with older kernel. IMHO, it's > acceptable > because Xen on ARM is still on Tech Preview and the hypercall ABI is not yet > freezed. How does a guest ascertain which API to use ? How does the patch ensure new kernels on existing hypervisor versions don't break ? What is the failure case given the alignment change seems potentially to produce valid but incorrect I/O requests - can it cause corruption ? It seems to me you should be defining struct blkif_request_rw_v2 and using the correct version according to which API the hypervisor requires, not just breaking it. Alan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
