From: Keith Busch <kbusch@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Michael Kropaczek <michael.kropaczek@solidigm.com>,
linux-nvme@lists.infradead.org, Jens Axboe <axboe@fb.com>,
Sagi Grimberg <sagi@grimberg.me>
Subject: Re: [PATCH v2 0/1] nvme: Fix problem when booting from NVMe drive was leading to a hang.
Date: Tue, 5 Mar 2024 08:17:59 -0700 [thread overview]
Message-ID: <Zec3p1bU_aTJJmF5@kbusch-mbp.dhcp.thefacebook.com> (raw)
In-Reply-To: <20240305135100.GC2063@lst.de>
On Tue, Mar 05, 2024 at 02:51:00PM +0100, Christoph Hellwig wrote:
> > + /*
> > + * On certain host architectures/HW, DRAM was keeping memory contents over reboot-cycles.
> > + * It was observed that certain controllers were accessing host memory after
> > + * resetting which led to undefined state preventing proper initialization.
> > + */
>
> Block comments should never span 80 characters. But more importantly
> I don't even think we need this comment at all, this is a clear bug
> fix and the code is self-describing.
It sounds like a firmware bug. Spec says:
"The host memory resources are not persistent in the controller across
a reset event."
Exiting a shutdown state requires a CC.EN transition, which is a reset
event.
It still may be good practice for the host driver to explicitly disable
host memory, but as I said last time, doing this in the shutdown path
deadlocks if the drive fails to produce a response, which is why we
removed it in the first place.
next prev parent reply other threads:[~2024-03-05 15:18 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-04 18:25 [PATCH v2 0/1] nvme: Fix problem when booting from NVMe drive was leading to a hang Michael Kropaczek
2024-03-05 13:51 ` Christoph Hellwig
2024-03-05 15:17 ` Keith Busch [this message]
2024-03-05 17:49 ` Michael Kropaczek
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