On Thu, Sep 26, 2019 at 8:41 AM Alex Bennée <alex.ben...@linaro.org> wrote: > > > Thomas Huth <th...@redhat.com> writes: > > > On 26/09/2019 15.46, Christian Borntraeger wrote: > >> > >> > >> On 26.09.19 14:58, Daniel P. Berrangé wrote: > >>> On Thu, Sep 26, 2019 at 08:50:36AM +0100, Peter Maydell wrote: > >>>> On Thu, 26 Sep 2019 at 00:31, Alex Bennée <alex.ben...@linaro.org> wrote: > >>>>> > >>>>> The 32 bit hosts are already a second class citizen especially with > >>>>> support for running 64 bit guests under TCG. We are also limited by > >>>>> testing as actual working 32 bit machines are getting quite rare in > >>>>> developers personal menageries. For TCG supporting newer types like > >>>>> Int128 is a lot harder with 32 bit calling conventions compared to > >>>>> their larger bit sized cousins. Fundamentally address space is the > >>>>> most useful thing for the translator to have even for a 32 bit guest a > >>>>> 32 bit host is quite constrained. > >>>>> > >>>>> As far as I'm aware 32 bit KVM users are even less numerous. Even > >>>>> ILP32 doesn't make much sense given the address space QEMU needs to > >>>>> manage. > >>>> > >>>> For KVM we should wait until the kernel chooses to drop support, > >>>> I think. > >>> > >>> What if the kernel is waiting for QEMU to drop support too ;-P > >> > >> For what its worth on kvm/s390 we never cared about implementing > >> 32 bit. > > > > Looking at tcg/s390/tcg-target.inc.c : > > > > ... > > /* We only support generating code for 64-bit mode. */ > > #if TCG_TARGET_REG_BITS != 64 > > #error "unsupported code generation mode" > > #endif > > ... > > > > ... it seems to me that TCG does not support 32-bit on s390 either. I > > think we can remove s390 (32-bit) from the list completely? > > It's the same for riscv32 I think.
I think riscv32 host *should* work, although I don't think it was ever tested. Considering that we have enough trouble keeping the riscv32 kernel booting it's probably ok to drop it from QEMU. Alistair > > > > > Thomas > > > -- > Alex Bennée >
