Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759411Ab3FCQPQ (ORCPT ); Mon, 3 Jun 2013 12:15:16 -0400 Received: from smtp.nue.novell.com ([195.135.221.5]:52250 "EHLO smtp.nue.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759038Ab3FCQO1 (ORCPT ); Mon, 3 Jun 2013 12:14:27 -0400 Subject: Re: [PATCH] Modify UEFI anti-bricking code From: joeyli To: Matthew Garrett Cc: rja@sgi.com, mingo@kernel.org, torvalds@linux-foundation.org, bp@alien8.de, jkosina@suse.cz, matt.fleming@intel.com, linux-efi@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, hpa@linux.intel.com, akpm@linux-foundation.org, oneukum@suse.de In-Reply-To: <1370117180-1712-1-git-send-email-matthew.garrett@nebula.com> References: <1370117180-1712-1-git-send-email-matthew.garrett@nebula.com> Content-Type: text/plain; charset="UTF-8" Date: Tue, 04 Jun 2013 00:13:40 +0800 Message-ID: <1370276021.30695.4.camel@linux-s257.site> Mime-Version: 1.0 X-Mailer: Evolution 2.28.2 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2371 Lines: 67 於 六，2013-06-01 於 16:06 -0400，Matthew Garrett 提到： > + unsigned long dummy_size = remaining_size + 1024; > + void *dummy = kmalloc(dummy_size, GFP_ATOMIC); > + efi_char16_t efi_name[6] = { 'D', 'U', 'M', 'M', 'Y', 0 }; > + efi_guid_t guid = EFI_GUID(0x4424ac57, 0xbe4b, 0x47dd, 0x9e, > + 0x97, 0xed, 0x50, 0xf0, 0x9f, 0x92, > + 0xa9); > + > + status = efi.set_variable(efi_name, &guid, attributes, > + dummy_size, dummy); > + > + if (status == EFI_SUCCESS) { > + /* > + * This should have failed, so if it didn't make sure > + * that we delete it... > + */ > + efi.set_variable(efi_name, &guid, attributes, 0, > + dummy); > + } Oliver raised a question for if power fails between that succesful attempt and the deletion? Due to the create/delete operating are not atomic, I think that will be better we try to delete DUMMY object in efi_enter_virtual_mode() or when efivars initial. The following diff tested on OVMF for delete DUMMY object when system boot, for reference. Thanks a lot! Joey Lee diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index 63e167a..72770b0 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -861,6 +861,10 @@ void __init efi_enter_virtual_mode(void) u64 end, systab, start_pfn, end_pfn; void *p, *va, *new_memmap = NULL; int count = 0; + efi_char16_t efi_name[6] = { 'D', 'U', 'M', 'M', 'Y', 0 }; + efi_guid_t guid = EFI_GUID(0x4424ac57, 0xbe4b, 0x47dd, 0x9e, + 0x97, 0xed, 0x50, 0xf0, 0x9f, 0x92, + 0xa9); efi.systab = NULL; @@ -981,6 +985,9 @@ void __init efi_enter_virtual_mode(void) runtime_code_page_mkexec(); kfree(new_memmap); + + /* clean DUMMY object */ + efi.set_variable(efi_name, &guid, 0, 0, NULL); } /* -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/