Message ID | 20230901194627.1214811-13-dbarboza@ventanamicro.com |
---|---|
State | New |
Headers | show |
Series | riscv: 'max' CPU, detect user choice in TCG | expand |
On 1/9/23 21:46, Daniel Henrique Barboza wrote: > The 'any' CPU type was introduced in commit dc5bd18fa5725 ("RISC-V CPU > Core Definition"), being around since the beginning. It's not an easy > CPU to use: it's undocumented and its name doesn't tell users much about > what the CPU is supposed to bring. 'git log' doesn't help us either in > knowing what was the original design of this CPU type. > > The closest we have is a comment from Alistair [1] where he recalls from > memory that the 'any' CPU is supposed to behave like the newly added > 'max' CPU. He also suggested that the 'any' CPU should be removed. > > The default CPUs are rv32 and rv64, so removing the 'any' CPU will have > impact only on users that might have a script that uses '-cpu any'. > And those users are better off using the default CPUs or the new 'max' > CPU. > > We would love to just remove the code and be done with it, but one does > not simply remove a feature in QEMU. We'll put the CPU in quarantine > first, letting users know that we have the intent of removing it in the > future. > > [1] https://lists.gnu.org/archive/html/qemu-devel/2023-07/msg02891.html > > Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com> > Reviewed-by: Alistair Francis <alistair.francis@wdc.com> > Reviewed-by: Andrew Jones <ajones@ventanamicro.com> > --- > docs/about/deprecated.rst | 12 ++++++++++++ > target/riscv/cpu.c | 5 +++++ > 2 files changed, 17 insertions(+) Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst index 92a2bafd2b..7277d4e8a4 100644 --- a/docs/about/deprecated.rst +++ b/docs/about/deprecated.rst @@ -371,6 +371,18 @@ QEMU's ``vhost`` feature, which would eliminate the high latency costs under which the 9p ``proxy`` backend currently suffers. However as of to date nobody has indicated plans for such kind of reimplementation unfortunately. +RISC-V 'any' CPU type ``-cpu any`` (since 8.2) +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +The 'any' CPU type was introduced back in 2018 and has been around since the +initial RISC-V QEMU port. Its usage has always been unclear: users don't know +what to expect from a CPU called 'any', and in fact the CPU does not do anything +special that isn't already done by the default CPUs rv32/rv64. + +After the introduction of the 'max' CPU type, RISC-V now has a good coverage +of generic CPUs: rv32 and rv64 as default CPUs and 'max' as a feature complete +CPU for both 32 and 64 bit builds. Users are then discouraged to use the 'any' +CPU type starting in 8.2. Block device options '''''''''''''''''''' diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c index 365c2b3b56..0dae259e02 100644 --- a/target/riscv/cpu.c +++ b/target/riscv/cpu.c @@ -1522,6 +1522,11 @@ static void riscv_cpu_realize(DeviceState *dev, Error **errp) RISCVCPUClass *mcc = RISCV_CPU_GET_CLASS(dev); Error *local_err = NULL; + if (object_dynamic_cast(OBJECT(dev), TYPE_RISCV_CPU_ANY) != NULL) { + warn_report("The 'any' CPU is deprecated and will be " + "removed in the future."); + } + cpu_exec_realizefn(cs, &local_err); if (local_err != NULL) { error_propagate(errp, local_err);