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Re: [PATCH v1 4/4] xen/arm: mpu: Disable secondary cpu bringup
- To: Julien Grall <julien@xxxxxxx>, Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- From: Ayan Kumar Halder <ayankuma@xxxxxxx>
- Date: Fri, 6 Sep 2024 15:29:11 +0100
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- Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>, Bertrand Marquis <bertrand.marquis@xxxxxxx>, Michal Orzel <michal.orzel@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
- Delivery-date: Fri, 06 Sep 2024 14:29:36 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 28/08/2024 20:24, Julien Grall wrote:
Hi Ayan,
Hi Julien,
The title is a bit confusing. It implies seconary CPU bringup used to
work on the MPU. However, you are adding a stub for
enable_secondary_cpu_mm.
Also, I am not entirely this is really sufficient to disable CPU
bringup. There will be plenty of initialization done for secondary CPUs.
I agree. init_secondary() has already been invoked before this.
I would suggest to update NR_CPUS to 1 for MPU so we will fail early.
Yes, I will do this.
For the title, how about
xen/arm: mpu: Implement a dummy enable_secondary_cpu_mm
On 23/08/2024 17:31, Ayan Kumar Halder wrote:
Secondary cpus are put in WFE state. We do not support SMP at this time.
Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>
---
xen/arch/arm/arm64/mpu/head.S | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/xen/arch/arm/arm64/mpu/head.S
b/xen/arch/arm/arm64/mpu/head.S
index 2b023c346a..1579ac0408 100644
--- a/xen/arch/arm/arm64/mpu/head.S
+++ b/xen/arch/arm/arm64/mpu/head.S
@@ -68,3 +68,12 @@ ENTRY(enable_boot_cpu_mm)
ret
ENDPROC(enable_boot_cpu_mm)
+
+/*
+ * Secondary cpu has not yet been supported on MPU systems. We will
block the
+ * secondary cpu bringup at this stage.
+ */
+ENTRY(enable_secondary_cpu_mm)
Can we print a message so it is easier to spot that
enable_secondary_cpu_mm is not properly implemented?
yes, something like this
PRINT("- SMP NOT SUPPORTED -\r\n")
- Ayan
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