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Re: [Qemu-devel] [PATCH v7 26/27] tcg: enable MTTCG by default for ARM o
Re: [Qemu-devel] [PATCH v7 26/27] tcg: enable MTTCG by default for ARM on x86 hosts
Fri, 20 Jan 2017 10:53:35 +0000
mu4e 0.9.19; emacs 220.127.116.11
Pranith Kumar <address@hidden> writes:
> Alex Bennée writes:
>> This enables the multi-threaded system emulation by default for ARMv7
>> and ARMv8 guests using the x86_64 TCG backend. This is because on the
>> guest side:
>> - The ARM translate.c/translate-64.c have been converted to
>> - use MTTCG safe atomic primitives
>> - emit the appropriate barrier ops
>> - The ARM machine has been updated to
>> - hold the BQL when modifying shared cross-vCPU state
>> - defer cpu_reset to async safe work
>> All the host backends support the barrier and atomic primitives but
>> need to provide same-or-better support for normal load/store
>> Signed-off-by: Alex Bennée <address@hidden>
>> +/* This defines the natural memory order supported by this
>> + * architecture before guarantees made by various barrier
>> + * instructions.
>> + *
>> + * The x86 has a pretty strong memory ordering which only really
>> + * allows for some stores to be re-ordered after loads.
>> + */
>> +#include "tcg-mo.h"
>> +static inline int get_tcg_target_mo(void)
>> + return TCG_MO_ALL & ~TCG_MO_LD_ST;
> Shouldn't this be TCG_MO_ALL & ~TCG_MO_ST_LD?
The case that x86 doesn't handle normally is store-after-load which is
what I assumed TCG_MO_LD_ST was. Perhaps we need some better comments
for each of the enums?
[Qemu-devel] [PATCH v7 26/27] tcg: enable MTTCG by default for ARM on x86 hosts, Alex Bennée, 2017/01/19
[Qemu-devel] [PATCH v7 18/27] cputlb: introduce tlb_flush_*_all_cpus, Alex Bennée, 2017/01/19
[Qemu-devel] [PATCH v7 20/27] target-arm: ensure BQL taken for ARM_CP_IO register access, Alex Bennée, 2017/01/19
[Qemu-devel] [PATCH v7 19/27] target-arm/powerctl: defer cpu reset work to CPU context, Alex Bennée, 2017/01/19
[Qemu-devel] [PATCH v7 27/27] target-ppc: take global mutex for set_irq, Alex Bennée, 2017/01/19
[Qemu-devel] [PATCH v7 24/27] target-arm: introduce ARM_CP_EXIT_PC, Alex Bennée, 2017/01/19
- Re: [Qemu-devel] [PATCH v7 14/27] cputlb: tweak qemu_ram_addr_from_host_nofail reporting, (continued)