From mboxrd@z Thu Jan 1 00:00:00 1970 From: linux@arm.linux.org.uk (Russell King - ARM Linux) Date: Sun, 12 Apr 2015 20:14:21 +0100 Subject: how to mapping device memory in head.S In-Reply-To: References: Message-ID: <20150412191420.GP12732@n2100.arm.linux.org.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Sun, Apr 12, 2015 at 08:23:59PM +0800, yoma sophian wrote: > hi all: > I need to map peripheral address in head.S for early usage. Basically, you do not. Please explain in detail what you're trying to do. > 1. CONFIG_DEBUG_LL is using short-descriptor 1st-level section > descriptor formats. Is it possible to use short-descriptor 2nd-level > small page descriptor in head.S? Definitely not, there is no memory management at that stage to allocate a 2nd level descriptor table. > 2. The peripheral mapping virtual address created in head.S is need to > access even after paging_init. Is it possible to put the mapping in > the persistent mapping in head.S? No, we don't support that. -- FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up according to speedtest.net.