From: Timur Tabi <ttabi@nvidia.com>
To: "nouveau@lists.freedesktop.org" <nouveau@lists.freedesktop.org>,
"lyude@redhat.com" <lyude@redhat.com>
Cc: "bskeggs@redhat.com" <bskeggs@redhat.com>,
"kherbst@redhat.com" <kherbst@redhat.com>,
"airlied@redhat.com" <airlied@redhat.com>,
"justinstitt@google.com" <justinstitt@google.com>,
"dri-devel@lists.freedesktop.org"
<dri-devel@lists.freedesktop.org>,
"keescook@chromium.org" <keescook@chromium.org>,
"airlied@gmail.com" <airlied@gmail.com>,
"dakr@redhat.com" <dakr@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"daniel@ffwll.ch" <daniel@ffwll.ch>
Subject: Re: [PATCH 1/2] drm/nouveau/firmware: Fix SG_DEBUG error with nvkm_firmware_ctor()
Date: Sun, 28 Apr 2024 18:19:55 +0000 [thread overview]
Message-ID: <a2c4681b900796f9ac47b61b802d9134f9a915b3.camel@nvidia.com> (raw)
In-Reply-To: <35b0ffe54f5e4077d5ebee6b82ae9ccd568dd77d.camel@redhat.com>
On Sun, 2024-04-28 at 11:52 -0400, Lyude Paul wrote:
> But we can't get a page pointer from an allocation made by
> dma_alloc_coherent() - but we can from vmalloc(). I'll fix the patch
> explanation in the next version, I have to send out another version
> anyhow since I realized that patch #2 still needs one more check to
> work properly
Glad my confusion was helpful! You wouldn't happent to know why this
statement is true?
DMA allocations can never be turned back into a page pointer
I'm guessing DMA allocations are taken from some memory pool that isn't
tracked using page pointers, but I don't understand why. It seems weird that
you can have a virtual address to the buffer, therefore it is surely mapped on
a page-by-page basis, so why are there no page pointers?
next prev parent reply other threads:[~2024-04-28 18:20 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-26 15:41 Lyude Paul
2024-04-26 15:41 ` [PATCH 2/2] drm/nouveau/gsp: Use the sg allocator for level 2 of radix3 Lyude Paul
2024-04-29 6:03 ` Dave Airlie
2024-04-29 17:54 ` Lyude Paul
2024-04-26 15:47 ` [PATCH 1/2] drm/nouveau/firmware: Fix SG_DEBUG error with nvkm_firmware_ctor() Timur Tabi
2024-04-28 15:52 ` Lyude Paul
2024-04-28 18:19 ` Timur Tabi [this message]
2024-04-29 18:23 ` [PATCH v2 " Lyude Paul
2024-04-29 18:23 ` [PATCH v2 2/2] drm/nouveau/gsp: Use the sg allocator for level 2 of radix3 Lyude Paul
2024-04-29 23:16 ` [PATCH v2 1/2] drm/nouveau/firmware: Fix SG_DEBUG error with nvkm_firmware_ctor() David Airlie
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