From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: [PATCH v2 1/3] x86, boot: add mmio serial during compressed boot Date: Sat, 13 Jul 2013 07:53:37 -0700 Message-ID: <51E169F1.5010301@zytor.com> References: <1373659660-31123-1-git-send-email-keescook@chromium.org> <20130712203802.GA14702@www.outflux.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-doc-owner@vger.kernel.org To: Yinghai Lu Cc: Kees Cook , "Eric W. Biederman" , Linux Kernel Mailing List , Rob Landley , Thomas Gleixner , Ingo Molnar , the arch/x86 maintainers , Greg Kroah-Hartman , linux-doc@vger.kernel.org, linux-serial@vger.kernel.org List-Id: linux-serial@vger.kernel.org On 07/12/2013 11:47 PM, Yinghai Lu wrote: > > for 32 bit, that is ok. > for 64 bit via 32bit bootloader, arch/x86/boot/compressed/head_64.S > will set page table for first 4G still ok. > for 64 bit via 64bit loader, like kexec via bzImage64, First Kernel/Kexec only > set ident mapping for usable range, so mmio just under 64 is not mapped. > > Looks like we need to update boot.txt to add requirement for 64bit bootloader > that 0-4G need to be all ident mapping? > I think that is an unrealistic requirement, especially if this is the sole user. -hpa