From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Howells <dhowells@redhat.com>
Subject: Re: [PATCH] CONFIG_PACKET_MMAP should depend on MMU
Date: Fri, 20 Apr 2007 09:58:52 +0100
Message-ID: <2181.1177059532@redhat.com>
References: <6d6a94c50704200139vb9b24f6y77a6d23544c8f7b9@mail.gmail.com>  <200704091146.32346.rgetz@blackfin.uclinux.org> <1176112223.17975.8.camel@roc-desktop> <9561.1176209728@redhat.com> <200704101952.05380.rgetz@blackfin.uclinux.org> <6d6a94c50704170336l62fc9ael1e58197e6c3853ba@mail.gmail.com> <2817.1176910411@redhat.com> <6d6a94c50704192146k5bbe2aefr31fa5726bf1c1e54@mail.gmail.com> <1016.1177055893@redhat.com>
Cc: "Robin Getz" <rgetz@blackfin.uclinux.org>, uaca@alumni.uv.es,
	bryan.wu@analog.com, "Alan Cox" <alan@lxorguk.ukuu.org.uk>,
	waltje@uwalt.nl.mugnet.org, netdev@vger.kernel.org,
	"Andrew Morton" <akpm@osdl.org>,
	"Linux Kernel" <linux-kernel@vger.kernel.org>
To: "Aubrey Li" <aubreylee@gmail.com>
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Aubrey Li <aubreylee@gmail.com> wrote:

> as checked in packet_set_ring, buffer size must be a multiple of PAGE_SIZE,
> --------------------packet_set_ring------------------------
> if (unlikely(req->tp_block_size & (PAGE_SIZE - 1)))
> 
> So why not use __get_free_pages rather than kmalloc,

Because kmalloc() may be able to get us a smaller chunk of memory.  Actually,
calling __get_free_pages() might be a better, and then release the excess
pages.

> so that we have pagetables to count?

There are no pagetables in NOMMU-mode.

David