From mboxrd@z Thu Jan 1 00:00:00 1970 From: sk.syed2@gmail.com (sk.syed2) Date: Wed, 30 Mar 2011 14:25:28 -0500 Subject: ARM : Kernel : Setting up of MMU in head.S In-Reply-To: References: Message-ID: To: kernelnewbies@lists.kernelnewbies.org List-Id: kernelnewbies.lists.kernelnewbies.org > The 2 lines above > 1:? orr??? r3, r7, r5, lsl #20??? ??? @ flags + kernel base ==> Correct > ??? str??? r3, [r4, r5, lsl #2]??? ??? @ identity mapping? ==> ?? > > create a section entry using index based on physical address. Lets say before mmu is turned on PC is at physical address XXX, also say at XXX there is going to be mmu on instruction. The next instruction fetch would be from XXX + 4 which would now be VIRTUAL address(as mmu is turned on), which should still get converted to (via page tables set up as above) to XXX + 4 (in physical). This is called identity mapping as specified in the comments. Hope this helps. -syed