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Re: [Qemu-ppc] [PATCH for-2.13 02/10] spapr: Remove support for PowerPC
Re: [Qemu-ppc] [PATCH for-2.13 02/10] spapr: Remove support for PowerPC 970 with pseries machine type
Fri, 20 Apr 2018 07:58:36 +0200
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On 19.04.2018 19:21, Greg Kurz wrote:
> On Tue, 17 Apr 2018 17:17:14 +1000
> David Gibson <address@hidden> wrote:
>> Current POWER cpus allow for a VRMA, a special mapping which describes a
>> guest's view of memory when in real mode (MMU off, from the guest's point
>> of view). Older cpus didn't have that which meant that to support a guest
>> a special host-contiguous region of memory was needed to give the guest its
>> Real Mode Area (RMA).
>> This was useful in the early days of KVM on Power to allow it to be tested
>> on PowerPC 970 chips as used in Macintosh G5 machines. Now, however, those
>> machines are so old as to be irrelevant, and the host kernel has long since
>> dropped support for this mode. It hasn't been tested in ages either.
>> So, to simplify the code, drop the support from qemu as well.
> So this could possibly break TCG guests with 970, which happens to be
> bootable with the current code ?
> $ cat /etc/redhat-release
> Red Hat Enterprise Linux Server release 6.9 (Santiago)
> $ cat /proc/cpuinfo
> processor : 0
> cpu : PPC970, altivec supported
> clock : 1000.000000MHz
> revision : 2.2 (pvr 0039 0202)
> timebase : 512000000
> platform : pSeries
> model : IBM pSeries (emulated by qemu)
> machine : CHRP IBM pSeries (emulated by qemu)
> I guess nobody uses this setup, but my understanding is that some
> rules must be followed when it comes to removing something that
> Maybe add a warning if 970 is used, and turn it into an error in two releases
> along with this patch ?
Right, we've got a process for deprecating old features, so please
follow that process.
[Qemu-ppc] [PATCH for-2.13 07/10] spapr: Make a helper to set up cpu entry point state, David Gibson, 2018/04/17
[Qemu-ppc] [PATCH for-2.13 09/10] target/ppc: Don't bother with MSR_EP in cpu_ppc_set_papr(), David Gibson, 2018/04/17
[Qemu-ppc] [PATCH for-2.13 02/10] spapr: Remove support for PowerPC 970 with pseries machine type, David Gibson, 2018/04/17
Re: [Qemu-ppc] [PATCH for-2.13 02/10] spapr: Remove support for PowerPC 970 with pseries machine type, Greg Kurz, 2018/04/20
[Qemu-ppc] [PATCH for-2.13 05/10] spapr: Move PAPR mode register initialization to spapr code, David Gibson, 2018/04/17
[Qemu-ppc] [PATCH for-2.13 06/10] target/ppc: Add ppc_store_lpcr() helper, David Gibson, 2018/04/17
[Qemu-ppc] [PATCH for-2.13 04/10] spapr: Set compatibility mode before the rest of spapr_cpu_reset(), David Gibson, 2018/04/17
- Re: [Qemu-ppc] [PATCH for-2.13 01/10] spapr: Avoid redundant calls to spapr_cpu_reset(), (continued)