From: Boris Ostrovsky Subject: Re: [PATCH 5/9] apm32: remove paravirt_enabled() use Date: Fri, 19 Feb 2016 10:08:43 -0500 Message-ID: <56C72FFB.5090105@oracle.com> References: <1455887316-9223-1-git-send-email-mcgrof@kernel.org> <1455887316-9223-6-git-send-email-mcgrof@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1455887316-9223-6-git-send-email-mcgrof@kernel.org> Sender: linux-kernel-owner@vger.kernel.org To: "Luis R. Rodriguez" , bp@alien8.de Cc: x86@kernel.org, linux-kernel@vger.kernel.org, luto@amacapital.net, rusty@rustcorp.com.au, david.vrabel@citrix.com, konrad.wilk@oracle.com, xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On 02/19/2016 08:08 AM, Luis R. Rodriguez wrote: > There is already a check for apm_info.bios == 0, the > apm_info.bios is set from the boot_params.apm_bios_info. > Both Xen and lguest, which are also the only ones that set > paravirt_enabled to true) do never set the apm_bios_info, > the paravirt_enabled() check is simply not needed. We need to guarantee that boot_params is filled with zeroes. On baremetal path we clear .bss (which is where boot_params live) before copying data from zero page. So we need to at least memset(&boot_params, 0, sz) in xen_start_kernel(). Better yet, clear whole .bss. (This applies to the next patch as well). -boris