Fam Zheng <f...@redhat.com> writes: > On Fri, 02/03 14:35, Markus Armbruster wrote: >> > I guess the painpoint is "okay, what the heck does the machine support >> > then?" - >> >> At the place where we can reliably detect orphaned drives regardless of >> what the machine initialization code does, we have no idea. >> >> > that "3 > 2" is the good part of the old message. >> >> At the places that actually adopt drives, we know. But there are many >> of them. Just three check for orphans. One of them gets it right >> (ide/core.c), one of them gets it wrong (mips_jazz.c), and one of them >> sets a problematic example (sun4m.c): if copied to a machine that lets >> users configure additional SCSI HBAs, it would break if=scsi for those. >> Dampens my enthusiasm for improving the error message by adding similar >> checks to all the places that adopt drives. >> >> We could make machines declare what they support. Better, I think. So >> if you have a burning desire to leave your mark in git-blame for every >> machine... > > Could you please remind me the situation about if=scsi across all machines? If > it is simply legacy and it's recommended to use "-drive if=none" and "-device > ...", I think saying this in the error message is enough; or if "if=scsi" is a > valid way for some machines, then maybe we can declare support limits found > with > your script?
Short story: once my followup series "[PATCH 0/3] hw: Deprecate unwanted use -drive if=scsi" is in, if=scsi is deprecated except for machine types magnum pica61 LX SPARCClassic SPARCbook SS-10 SS-20 SS-4 SS-5 SS-600MP Voyager realview-eb realview-eb-mpcore versatileab versatilepb pseries-*. Documenting what they support would be feasible. Long story: it's... complicated. Ideally, -drive if=T,... (T!=none) would be sugar for a -drive / -device combo. It actually is for if=virtio: drive_new() desugars it. All the others are implemented by machine-specific ad hoc code, i.e. machine initialization creates devices however it sees fit. For modern devices, what's done is often pretty much equivalent to a -device. For instance, a PC machine type's action for if=ide,media=disk,bus=B,unit=U is pretty much equivalent to -device ide-hd,bus=ide.B,unit=U. See also docs/qdev-device-use.txt. Desugaring details depend on the machine, and are code, not data. Data would be easier to find and document. For non-qdevified devices, we're even farther from a clean desugaring, simply because these are not available with -device, but can only be created by code. For instance, some machine types implement if=sd with the non-qdevified hw/sd/sd.c; grep for sd_init(). So, we're not yet ready for deprecating if!=none. But you asked for if=scsi specifically. Only a few machines have a SCSI HBA onboard, and therefore adopt if=scsi drives: magnum pica61 LX SPARCClassic SPARCbook SS-10 SS-20 SS-4 SS-5 SS-600MP Voyager. We're not deprecating this usage. A few more create SCSI HBAs on demand: realview-eb realview-eb-mpcore versatileab versatilepb pseries-* pc*. My followup series deprecates it for pc* only. Finally, there's some special SCSI magic: most SCSI HBAs adopt if=scsi drives independend of machine initialization. My followup series deprecates that.
