[...] >>> >>> By the way the patch works only for -blockdev configuration which is >>> available since QEMU 2.10 AFAIK. So we could purse to support 2.10, 2.11, >>> 2.12 and 3.0 version in principle. >> >> Ah true, the --blockdev option is required. >> >> I've put the "artificial" point in time of 2.12 because that when I >> recall Berto making adjustments to the cache size algorithms and when >> the @l2-cache-entry-size appeared in qapi/block-core.json. I think prior >> to those changes the algorithm was even more difficult to decipher. >> > > UPDATE > > Turns out -blockdev will be supported only starting from QEMU 3.0.0 according > to [1]. I thought 2.10 and further versions will be supported too because grepped > 'qdev' in tests/qemucapabilitiesdata/ - turns out I found support for > query-block command :) > > So I think extra complexity to support just 3.0.0 is unnessesary. > > Nikolay Since I see you pinged on public IRC - I'm OK with using -blockdev as the base - it's the "implementation detail" that perhaps can be noted when deciding whether to apply/support the cache size. I think then the only 'difference' would be the QEMU 3.1 change that allows for a more true maximum value. Since that "detail" would/should be hidden from consumers, maybe you just use that QEMU_CAPS_QCOW2_L2_CACHE_SIZE value to determine whether some arbitrarily, but algorithmic value is used or if the cap is there just use INT64_MAX. And by the former I mean, consider what the default values are, do some math and use that as the max with the appropriate explanation. John Also just so you're aware - like many other Red Hat associates, I'm "technically" on vacation until after Jan 1. It's our annual shutdown period and while > > [1] [PATCHv2 62/62] DO NOT APPLY: Enable QEMU_CAPS_BLOCKDEV if 'query-blockstats' works with -blockdev > https://www.redhat.com/archives/libvir-list/2018-August/msg00755.html > > --- a/src/qemu/qemu_capabilities.c > +++ b/src/qemu/qemu_capabilities.c > @@ -1307,6 +1307,7 @@ static struct virQEMUCapsStringFlags virQEMUCapsQMPSchemaQueries[] = { > { "blockdev-add/arg-type/+qcow2/encrypt/+luks/key-secret", QEMU_CAPS_QCOW2_LUKS }, > { "nbd-server-start/arg-type/tls-creds", QEMU_CAPS_NBD_TLS }, > { "screendump/arg-type/device", QEMU_CAPS_SCREENDUMP_DEVICE }, > + { "query-blockstats/ret-type/qdev", QEMU_CAPS_BLOCKDEV }, > }; > [...] -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
