Messages in this thread | | | Date | Thu, 5 Feb 2009 18:29:11 -0800 (PST) | From | Vira <> | Subject | Re: Mapping non-page aligned data to user |
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I am trying to map DMAed packets directly to contiguous user buffer (avoiding the copy)- thinking of how to skip the packet headers here.
Thx, -- vira
--- On Thu, 2/5/09, Robert Hancock <hancockrwd@gmail.com> wrote:
> From: Robert Hancock <hancockrwd@gmail.com> > Subject: Re: Mapping non-page aligned data to user > To: linux-kernel@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > Date: Thursday, February 5, 2009, 4:27 PM > Vira wrote: > > Hi, > > Is there a way to map a non-page aligned kernel > physical address to user virtual address? remap_pfn_range > and vm_insert_page operate only on page-aligned physical > addresses. > > > > If there is no such support, would it be too > complicated to try out > > writing something on my own to map non-page aligned > addresses (the data > > size is under my control - so I can make that a > multiple of page size)? > > > > Any suggestions appreciated. > > The CPU, and therefore the kernel, couldn't ensure that > the user doesn't write outside the mapped region of > kernel memory if it's not page aligned (the access > control is page granularity only). That seems like it would > be a show-stopper in most cases. > > What exactly is it you're trying to achieve with this? > > -- > To unsubscribe from this list: send the line > "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at > http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
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