linux-kernel - Re: [PATCH v16 6/9] irqchip: Add RISC-V advanced PLIC driver for direct-mode

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Message-ID: <87ms4eflvt.wl-maz@kernel.org>
Date: Sat, 22 Nov 2025 09:37:58 +0000
From: Marc Zyngier <maz@...nel.org>
To: niliqiang <ni_liqiang@....com>
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Subject: Re: [PATCH v16 6/9] irqchip: Add RISC-V advanced PLIC driver for direct-mode

On Fri, 21 Nov 2025 13:54:07 +0000,
niliqiang <ni_liqiang@....com> wrote:
>

[...]

> 2. But the OS enumerates them in random order upon each boot (first boot sequence ≠ second boot sequence)
> first boot sequence ~ # dmesg |grep -i "PCI Root"
> [ 8794.588531] ACPI: PCI Root Bridge [PC08] (domain 0006 [bus 80-ff])
> [ 8794.624478] ACPI: PCI Root Bridge [PC06] (domain 0005 [bus 00-ff])
> [ 8794.672741] ACPI: PCI Root Bridge [PC10] (domain 0008 [bus 00-ff])
> [ 8794.696680] ACPI: PCI Root Bridge [PC07] (domain 0006 [bus 00-7f])
> [ 8794.728234] ACPI: PCI Root Bridge [PC11] (domain 0009 [bus 00-ff])
> [ 8794.755098] ACPI: PCI Root Bridge [PC09] (domain 0007 [bus 00-ff])
> second boot sequence ~ # dmesg |grep -i "PCI Root"
> [ 8794.588531] ACPI: PCI Root Bridge [PC09] (domain 0007 [bus 00-ff])
> [ 8794.624478] ACPI: PCI Root Bridge [PC06] (domain 0005 [bus 00-ff])
> [ 8794.672741] ACPI: PCI Root Bridge [PC08] (domain 0006 [bus 80-ff])
> [ 8794.696680] ACPI: PCI Root Bridge [PC11] (domain 0009 [bus 00-ff])
> [ 8794.728234] ACPI: PCI Root Bridge [PC07] (domain 0006 [bus 00-7f])
> [ 8794.755098] ACPI: PCI Root Bridge [PC10] (domain 0008 [bus 00-ff])
> 
> This creates a critical issue: when NVMe devices are connected to
> these host bridges, the unpredictable kernel scanning sequence
> causes device identifiers (e.g., /dev/nvme0n1, /dev/nvme1n1) to
> change across reboots. In server environments, such device naming
> instability is unacceptable as it breaks storage configuration
> reliability and consistency.

You're barking up the wrong tree. It is *userspace*'s job to ensure
this consistency. That's why udev exists. That's why device and
partition UUIDs exist. In short, this isn't the kernel's job. The
kernel gives you all the tools you need already.

Thanks,

	M.

-- 
Jazz isn't dead. It just smells funny.