On Fri, Jan 22, 2010 at 10:52:29PM +0800, Liu, Jinsong wrote: > Gleb Natapov wrote: > > On Fri, Jan 22, 2010 at 06:54:42PM +0800, Liu, Jinsong wrote: > >> Gleb Natapov wrote: > >>> On Fri, Jan 22, 2010 at 05:08:32PM +0800, Liu, Jinsong wrote: > >>>> Gleb Natapov wrote: > >>>>> On Fri, Jan 22, 2010 at 10:15:44AM +0800, Liu, Jinsong wrote: > >>>>>> Gleb Natapov wrote: > >>>>>>> On Thu, Jan 21, 2010 at 07:48:23PM +0800, Liu, Jinsong wrote: > >>>>>>>>> From cb997030cba02e7e74a29b3d942aeba9808ed293 Mon Sep 17 > >>>>>>>>> 00:00:00 2001 > >>>>>>>> From: Liu, Jinsong <jinsong....@intel.com> > >>>>>>>> Date: Fri, 22 Jan 2010 03:18:46 +0800 > >>>>>>>> Subject: [PATCH] Setup vcpu add/remove infrastructure, > >>>>>>>> including madt bios_info and dsdt. > >>>>>>>> > >>>>>>>> 1. setup madt bios_info structure, so that static dsdt > >>>>>>>> get run-time madt info like checksum address, lapic > >>>>>>>> address, max cpu numbers, with least hardcode magic > >>>>>>>> number (realmode address of bios_info). > >>>>>>>> 2. setup vcpu add/remove dsdt infrastructure, including > >>>>>>>> processor related acpi objects and control methods. > >>>>>>>> vcpu add/remove will trigger SCI and then control > >>>>>>>> method _L02. By matching madt, vcpu number and > >>>>>>>> add/remove action were found, then by notify control > >>>>>>>> method, it will notify OS acpi driver. > >>>>>>>> > >>>>>>>> Signed-off-by: Liu, Jinsong <jinsong....@intel.com> > >>>>>>> It looks like AML code is a port of what we had in BOCHS bios > >>>>>>> with minor changes. Can you detail what is changed and why for > >>>>>>> easy review please? And this still doesn't work with Windows I > >>>>>>> assume. > >>>>>>> > >>>>>> > >>>>>> Yes, my work is based on BOCHS infrastructure, thanks BOCHS :) > >>>>>> I just change some minor points: > >>>>>> 1. explicitly define returen value of '_MAT' as 'buffer', > >>>>>> otherwise some linux acpi driver (i.e. linux 2.6.30) would parse > >>>>>> error which will handle it as 'integer' not 'buffer'; > >>>>>> 2. keep correct 'checksum' of madt when vcpu add/remove, > >>>>>> otherwise it will report 'checksum error' when using acpi tools > >>>>>> to get madt info if we add/remove vcpu; > >>>>>> 3. add '_EJ0' so that linux has acpi obj under > >>>>>> /sys/devices/LNXSYSTM:00, which is need for vcpu remove; > >>>>>> 4. on Method(PRSC, 0), just scan 'xxx' vcpus that qemu get from > >>>>>> cmdline para 'maxcpus=xxx', not all 256 vcpus, otherwise under > >>>>>> some dsdt processor define, it will result error; > >>>>> What kind of errors? Qemu should never set bit over maxcpus in > >>>>> PRS. > >>>>> > >>>> suppose cmdline define vcpus=4, maxvcpus=8 > >>>> in original BOCHS, will scan 15 lapic items start from lapic0 of > >>>> madt, where it only has maxvcpus lapic items in madt table, hence > >>>> there is risk to scan over boundary, scan to other acpi table, and > >>>> result in wrong vcpu online/offline status (in my test, I meet this > >>>> situation). Because of this reason, this patch limit scan maxvcpus > >>>> lapic of madt. > >>>> > >>> But what if cmdline will use vcpu=64? The idea was that \_PR scope > >>> will reside in its own ssdt and for each maxvcpus value there will > >>> be ssdt with exactly this number of processors. Ideally ssdt will be > >>> created dynamically like it is done now, but another solution is to > >>> create them at bios compilation time and load correct one at > >>> runtime. > >>> > >> > >> It's OK for vcpu=64. vcpu<maxvcpus. > >> if maxvcpus > processor defined in dsdt, it's OK since no risk scan > >> (bios only support 15 processor is another story); if processor > >> defined in dsdt > maxvcpus, it has risk to scan over boundary. > >> > >> > > Yes, correct. So why not export maxcpus to DSDT and at the beginning > > of NTFY check that Arg0 < maxcpus then? > > > > Yes, your solution also work. > In fact, we implicitly export maxcpus to DSDT by > struct bios_info { > ... > u32 max_cpus_byte; /* max cpus bitmap bytes */ > u32 max_cpus_bit; /* max cpus bitmap bits of last byte */ > }; > this indicate maxvcpus. > In this way it can reduce scan loop. > Actually your scan loop is twice as big as it was in BOCHS because of this tricks with bytes and bits.
> However, I think it's not key issue. Both are OK. > Just different implement way. > The AML code is hard to read as it is, so making it simpler is important. But the way I want to see this solved in seabios is to create exactly maxvcpu processors in _PR scope. This will solve MS SVVP problem too (BOCHS doesn't pass SVVP). -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html