From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <38581FEA.9E970D7A@ctam.com.au> Date: Thu, 16 Dec 1999 10:10:35 +1100 From: Brendan Simon Reply-To: bsimon@ctam.com.au MIME-Version: 1.0 CC: linuxppc-embedded Subject: linuxppc-embedded: memory map question. References: <19991215055541.23843.qmail@web301.mail.yahoo.com> <385725A3.A1C110DF@ctam.com.au> <385774B8.3405494B@iname.com> <3857EAF8.491F842@netx4.com> Content-Type: text/plain; charset=us-ascii Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: Dan Malek wrote: > As I have explained before, the IMMR and possibly a few other > board control registers must have physical addresses above > 0x80000000. This is because the early kernel initialization > will map these 1:1 virtual to physical. They are needed before > the kernel VM allocator has been initialized. If they are > below this address, they clash with the user virtual space, > so depending upon the loading of programs and libraries, you > left a big virtual hole into kernel managed hardware. My IMMR is 0xFF000000. I basically followed the BSE-IP stuff when I ported linuxppc to our own board. This is above 0x80000000 so this should be fine, but I do have some peripherals (LEDs, etc) mapped to memory lower than 0x8000000 (eg 0x20000000). Is this good or bad ? Would it be better if I memory mapped everything above 0x80000000 (except DRAM of course) ? Brendan Simon. ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/