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Re: [Qemu-riscv] [Qemu-devel] [PATCH] riscv: virt: Add cpu-topology DT n
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [Qemu-riscv] [Qemu-devel] [PATCH] riscv: virt: Add cpu-topology DT node. |
Date: |
Tue, 25 Jun 2019 13:27:11 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 |
On 6/25/19 12:41 PM, Daniel P. Berrangé wrote:
> On Tue, Jun 25, 2019 at 12:36:35PM +0200, Philippe Mathieu-Daudé wrote:
>> On 6/25/19 1:24 AM, Alistair Francis wrote:
>>> On Mon, Jun 24, 2019 at 3:57 PM Atish Patra <address@hidden> wrote:
>>>>
>>>> Currently, there is no cpu topology defined in RISC-V.
>>>> Define a device tree node that clearly describes the
>>>> entire topology. This saves the trouble of scanning individual
>>>> cache to figure out the topology.
>>>>
>>>> Here is the linux kernel patch series that enables topology
>>>> for RISC-V.
>>>>
>>>> http://lists.infradead.org/pipermail/linux-riscv/2019-June/005072.html
>>>>
>>>> CPU topology after applying this patch in QEMU & above series in kernel
>>>>
>>>> / # cat /sys/devices/system/cpu/cpu2/topology/thread_siblings_list
>>>> 2
>>>> / # cat /sys/devices/system/cpu/cpu2/topology/physical_package_id
>>>> 0
>>>> / # cat /sys/devices/system/cpu/cpu2/topology/core_siblings_list
>>>> 0-7
>>>>
>>>> Signed-off-by: Atish Patra <address@hidden>
>>>> ---
>>>> hw/riscv/virt.c | 21 +++++++++++++++++++--
>>>> 1 file changed, 19 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
>>>> index 84d94d0c42d8..da0b8aa18747 100644
>>>> --- a/hw/riscv/virt.c
>>>> +++ b/hw/riscv/virt.c
>>>> @@ -203,9 +203,12 @@ static void *create_fdt(RISCVVirtState *s, const
>>>> struct MemmapEntry *memmap,
>>>> qemu_fdt_setprop_string(fdt, nodename, "status", "okay");
>>>> qemu_fdt_setprop_cell(fdt, nodename, "reg", cpu);
>>>> qemu_fdt_setprop_string(fdt, nodename, "device_type", "cpu");
>>>> + qemu_fdt_setprop_cell(fdt, nodename, "phandle", cpu_phandle);
>>>> + qemu_fdt_setprop_cell(fdt, nodename, "linux,phandle",
>>>> cpu_phandle);
>>>> + int intc_phandle = phandle++;
>>>
>>> Don't declare variables in the middle of code. The variable must be
>>> declared at the start of a block.
>>
>> I guess this has been relaxed since we allow GNU C99:
>
> Even though we allow GNU C99 I think it is undesirable to declare variables
> in the middle of methods. This is especially true when combined with "goto"
> as you end up with undefined / uninitialized vairable contents at the jump
> target, if we've jumped over the variable declaration.
>
> We can't enforce location of variable declarations, but I'd really
> recommend we keep them all at the start of code blocks.
In this case I find it desirable:
for (int i = 0; ...) {
...
}
For the rest, I agree to keep them at the start of code block.
Regards,
Phil.