Re: [PATCH 1/3] uio: Allow handling of non page-aligned memory regions

From	Michal Sojka <sojkam1@fel.cvut.cz>
Newsgroups	linux.kernel
Subject	Re: [PATCH 1/3] uio: Allow handling of non page-aligned memory regions
Date	2017-03-16 14:40 +0100
Message-ID	<tlDNf-7rG-3@gated-at.bofh.it> (permalink)
References	<tipQu-1uF-21@gated-at.bofh.it> <tlyXf-3YD-7@gated-at.bofh.it> <tlD0S-6Rt-15@gated-at.bofh.it> <tlDDA-7mM-19@gated-at.bofh.it>
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On Thu, Mar 16 2017, Greg KH wrote:
> On Thu, Mar 16, 2017 at 01:45:50PM +0100, Michal Sojka wrote:
>> On Thu, Mar 16 2017, Greg KH wrote:
>> > On Tue, Mar 07, 2017 at 03:09:46PM +0100, Michal Sojka wrote:
>> >> Since commit b65502879556 ("uio: we cannot mmap unaligned page
>> >> contents") addresses and sizes of UIO memory regions must be
>> >> page-aligned. If the address in the BAR register is not page-aligned,
>> >> the mentioned commit forces the UIO driver to round the address down
>> >> to the page size. Then, there is no easy way for user-space to learn
>> >> the offset of the actual memory region within the page, because the
>> >> offset seen in the sysfs is calculated from the rounded address and
>> >> thus it is always zero.
>> >> 
>> >> Fix that problem by including the offset in struct uio_mem. UIO
>> >> drivers can set this field and its value is reported via sysfs.
>> >
>> > It is, where?
>> 
>> /sys/class/uio/uio0/maps/map0/offset
>
> Did you change the Documentation/ABI entry for it?

No, because it seems that UIO is not documented there.

-Michal

Thread

Re: [PATCH 1/3] uio: Allow handling of non page-aligned memory  regions Greg KH <gregkh@linuxfoundation.org> - 2017-03-16 09:30 +0100
  Re: [PATCH 1/3] uio: Allow handling of non page-aligned memory regions Michal Sojka <sojkam1@fel.cvut.cz> - 2017-03-16 13:50 +0100
    Re: [PATCH 1/3] uio: Allow handling of non page-aligned memory  regions Greg KH <gregkh@linuxfoundation.org> - 2017-03-16 14:30 +0100
      Re: [PATCH 1/3] uio: Allow handling of non page-aligned memory regions Michal Sojka <sojkam1@fel.cvut.cz> - 2017-03-16 14:40 +0100
        Re: [PATCH 1/3] uio: Allow handling of non page-aligned memory  regions Greg KH <gregkh@linuxfoundation.org> - 2017-03-16 15:10 +0100
          Re: [PATCH 1/3] uio: Allow handling of non page-aligned memory regions Michal Sojka <sojkam1@fel.cvut.cz> - 2017-03-16 15:30 +0100
      [PATCH v2 2/3] uio_mf624: Refactor memory info initialization Michal Sojka <sojkam1@fel.cvut.cz> - 2017-03-16 15:00 +0100
      [PATCH v2 3/3] uio_mf624: Align memory regions to page size and set correct offsets Michal Sojka <sojkam1@fel.cvut.cz> - 2017-03-16 15:00 +0100
      [PATCH v2 1/3] uio: Allow handling of non page-aligned memory regions Michal Sojka <sojkam1@fel.cvut.cz> - 2017-03-16 15:00 +0100

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