From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3910838C.986942D6@embeddededge.com> Date: Wed, 03 May 2000 15:52:44 -0400 From: Dan Malek MIME-Version: 1.0 To: Steve Rossi CC: Embedded Linux PPC List Subject: Re: allocating non-cacheable regions References: <39104A07.D997B6C5@ccrl.mot.com> Content-Type: text/plain; charset=us-ascii Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: Steve Rossi wrote: > > How do I allocate a region of memory that is flagged as being > non-cacheable? I am assuming you intend to do this on the 8xx processor as it doesn't make sense on others. It may also not make sense on the 8xx as it appears from testing that caching memory and push/invalidate during I/O is better...... For an example, look at the commproc.c or enet.c driver in the arch/ppc/8xx_io directory. When pages are allocated, the PTEs are tracked down and marked non-cache. > Does it have to be done at allocation or is it possible to mark a region > non-cacheable > after its been allocated? I haven't found a way to get the kernel to allocate non-cache regions of real memory. It would be nice if there was something along the lines of DMA attribute, or perhaps I am just not looking in the right place (and I am sure someone will point this out :-). All I/O space is uncached and guarded. -- Dan ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/