Re: [libvirt] [Qemu-devel] [PATCH for-2.9 00/17] target-i386: Implement query-cpu-model-expansion

> Is static really needed? I can understand why migration-safe might be > of interest, but can't see how "static" could help (I mean we have > static expansion for this purpose). Do you have anything special in > mind regarding exposing "static"? I didn't have any specific use case in mind. My main worry is to avoid letting management software make any assumptions about the returned data. If we don't add an explicit "static" field, a client might make some wrong assumptions just because some conditions are known to be always true on existing implementations. e.g.: a client could incorrectly assume that "query-cpu-model-expansion type=full" of a migration-safe model would always be static.

> Something like that would be cool. Unfortunately, e.g. on s390x some > CPUID-like data (e.g. STFL(E) and SCP info) is only available from > kernel space. So we can't simply run a user space script. However, > something like a kernel module would be possible (or even something like the > s390x pc-bios to simply read and dump the data). I meant a kernel binary, above. On x86, there are existing test cases on the autotest repository that run a very small kernel[1] that simply dumps CPUID data to the serial console. We could reuse it, or we could add a CPUID command to the qtest protocol. I'm not sure what's the best solution. We can try to use a similar approach on s390x to reuse code in the test script, but we can add arch-specific code to it if necessary.

[1] https://github.com/autotest/tp-qemu/tree/master/qemu/deps/cpuid/src