From: Guenter Roeck <linux@roeck-us.net>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Chris Leech <cleech@redhat.com>,
Nilesh Javali <njavali@marvell.com>,
Christoph Hellwig <hch@lst.de>,
John Meneghini <jmeneghi@redhat.com>,
Lee Duncan <lduncan@suse.com>,
Mike Christie <michael.christie@oracle.com>,
Hannes Reinecke <hare@kernel.org>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-scsi@vger.kernel.org,
GR-QLogic-Storage-Upstream@marvell.com,
Simon Horman <horms@kernel.org>
Subject: Re: [PATCH v6 1/4] uio: introduce UIO_MEM_DMA_COHERENT type
Date: Fri, 22 Mar 2024 08:23:13 -0700 [thread overview]
Message-ID: <71178af5-b52f-4d60-a438-1cf6b0ecb4d8@roeck-us.net> (raw)
In-Reply-To: <2024032203-dawn-crestless-4199@gregkh>
On 3/22/24 07:30, Greg Kroah-Hartman wrote:
> On Fri, Mar 22, 2024 at 07:16:19AM -0700, Guenter Roeck wrote:
>> On Mon, Feb 05, 2024 at 12:01:37PM -0800, Chris Leech wrote:
>>> Add a UIO memtype specifically for sharing dma_alloc_coherent
>>> memory with userspace, backed by dma_mmap_coherent.
>>>
>>> This is mainly for the bnx2/bnx2x/bnx2i "cnic" interface, although there
>>> are a few other uio drivers which map dma_alloc_coherent memory and will
>>> be converted to use dma_mmap_coherent as well.
>>>
>>> Signed-off-by: Nilesh Javali <njavali@marvell.com>
>>> Signed-off-by: Chris Leech <cleech@redhat.com>
>>> ---
>>
>> Building i386:allyesconfig ... failed
>> --------------
>> Error log:
>> drivers/uio/uio.c: In function 'uio_mmap_dma_coherent':
>> drivers/uio/uio.c:795:16: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
>> 795 | addr = (void *)mem->addr;
>> | ^
>
> So on 32bit systems phys_addr_t != the same size as (void *)? How is
> that possible? We also are doing an explicit cast here, how does this
> not work?
phys_addr_t is not always equivalent to the size of a pointer.
PHYS_ADDR_T_64BIT is a configuration option, after all, and it
is independent of "config 64BIT".
>
> Ah, do you have CONFIG_X86_PAE enabled? That would cause that mess,
> ick.
>
>
>> cc1: all warnings being treated as errors
>> make[5]: [scripts/Makefile.build:244: drivers/uio/uio.o] Error 1 (ignored)
>> drivers/uio/uio_dmem_genirq.c: In function 'uio_dmem_genirq_open':
>> drivers/uio/uio_dmem_genirq.c:63:39: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
>> 63 | uiomem->addr = addr ? (phys_addr_t) addr : DMEM_MAP_ERROR;
>> | ^
>> drivers/uio/uio_dmem_genirq.c: In function 'uio_dmem_genirq_release':
>> drivers/uio/uio_dmem_genirq.c:92:43: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
>> 92 | (void *) uiomem->addr,
>> | ^
>> cc1: all warnings being treated as errorsphys_addr_t
>> make[5]: [scripts/Makefile.build:244: drivers/uio/uio_dmem_genirq.o] Error 1 (ignored)
>> drivers/uio/uio_pruss.c: In function 'pruss_probe':
>> drivers/uio/uio_pruss.c:194:34: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
>> 194 | p->mem[2].addr = (phys_addr_t) gdev->ddr_vaddr;
>> | ^
>> cc1: all warnings being treated as errors
>>
>> Caused by this patch and "uio_dmem_genirq: UIO_MEM_DMA_COHERENT conversion" as well
>> as "uio_pruss: UIO_MEM_DMA_COHERENT conversion".
>>
>> I'd suggest to make uio dependent on 64 bit if 32 bit is no longer supported
>> to prevent waste of test builds resources.
>
> Perhaps disable it if PHYS_ADDR_T_64BIT is not enabled?
>
i386:allyesconfig sets
CONFIG_X86_HAVE_PAE=y
CONFIG_X86_PAE=y
CONFIG_PHYS_ADDR_T_64BIT=y
so that would not really help. The problem here is that this is a 32-bit build,
meaning pointers are 32 bit, while phys_addr_t is 64 bit. I did not check the
code, but it will simply not work if the pointer is supposed to reflect a
physical address. The new dependency would have to check if sizeof(void *) is
larger or equal to sizeof(phys_addr_t). Even then the code would need a double
cast since it is also possible that sizeof(void *) > sizeof(phys_addr_t).
Guenter
next prev parent reply other threads:[~2024-03-22 15:23 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-01 23:33 [PATCH v5 0/4] UIO_MEM_DMA_COHERENT for cnic/bnx2/bnx2x Chris Leech
2024-02-01 23:33 ` [PATCH v5 1/4] uio: introduce UIO_MEM_DMA_COHERENT type Chris Leech
2024-02-04 10:20 ` Simon Horman
2024-02-05 20:01 ` [PATCH v6 " Chris Leech
2024-02-12 6:56 ` Christoph Hellwig
2024-03-22 14:16 ` Guenter Roeck
2024-03-22 14:30 ` Greg Kroah-Hartman
2024-03-22 15:23 ` Guenter Roeck [this message]
2024-02-01 23:33 ` [PATCH v5 2/4] cnic,bnx2,bnx2x: use UIO_MEM_DMA_COHERENT Chris Leech
2024-02-02 19:08 ` Jakub Kicinski
2024-02-01 23:33 ` [PATCH v5 3/4] uio_pruss: UIO_MEM_DMA_COHERENT conversion Chris Leech
2024-02-01 23:34 ` [PATCH v5 4/4] uio_dmem_genirq: " Chris Leech
2024-02-04 10:19 ` Simon Horman
2024-02-05 19:53 ` Chris Leech
2024-02-05 20:02 ` [PATCH v6 " Chris Leech
2024-02-05 16:57 ` [PATCH v5 0/4] UIO_MEM_DMA_COHERENT for cnic/bnx2/bnx2x Alexander Lobakin
2024-02-05 19:51 ` Chris Leech
2024-02-06 15:54 ` Jakub Kicinski
2024-02-06 20:16 ` Lee Duncan
2024-02-21 18:28 ` Chris Leech
2024-02-28 18:20 ` Lee Duncan
2024-02-29 6:10 ` Greg Kroah-Hartman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=71178af5-b52f-4d60-a438-1cf6b0ecb4d8@roeck-us.net \
--to=linux@roeck-us.net \
--cc=GR-QLogic-Storage-Upstream@marvell.com \
--cc=cleech@redhat.com \
--cc=gregkh@linuxfoundation.org \
--cc=hare@kernel.org \
--cc=hch@lst.de \
--cc=horms@kernel.org \
--cc=jmeneghi@redhat.com \
--cc=lduncan@suse.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-scsi@vger.kernel.org \
--cc=michael.christie@oracle.com \
--cc=netdev@vger.kernel.org \
--cc=njavali@marvell.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).