Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 7 Oct 2001 13:54:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 7 Oct 2001 13:54:41 -0400 Received: from hermes.toad.net ([162.33.130.251]:41941 "EHLO hermes.toad.net") by vger.kernel.org with ESMTP id ; Sun, 7 Oct 2001 13:54:25 -0400 Subject: Re: Linux should not set the "PnP OS" boot flag From: Thomas Hood To: Alan Cox Cc: linux-kernel@vger.kernel.org In-Reply-To: In-Reply-To: Content-Type: text/plain Content-Transfer-Encoding: 7bit X-Mailer: Evolution/0.14 (Preview Release) Date: 07 Oct 2001 13:54:19 -0400 Message-Id: <1002477264.1004.9.camel@thanatos> Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Here's a slightly neater version of the patch which gives control over the DIAG bit also. We'd need config options for "CONFIG_SBF_DIAG" and "CONFIG_SBF_PNPOS". I'd like to say in defense of this patch that the more conservative thing to do _by default_ is to let the PnP BIOS configure devices before Linux boots. The cost SFAIK is only time. The cost of leaving devices unconfigured is, for some people, oopses. -- Thomas The patch: --- linux-2.4.10-ac7/arch/i386/kernel/bootflag.c Fri Oct 5 14:57:10 2001 +++ linux-2.4.10-ac7-fix/arch/i386/kernel/bootflag.c Sun Oct 7 13:45:41 2001 @@ -15,6 +15,13 @@ #include + +#define SBF_RESERVED (0x78) +#define SBF_PNPOS (1<<0) +#define SBF_BOOTING (1<<1) +#define SBF_DIAG (1<<2) +#define SBF_PARITY (1<<7) + struct sbf_boot { u8 sbf_signature[4]; @@ -59,7 +66,7 @@ return 0; if (sb.sbf_len == 39) - printk (KERN_WARNING "ACPI BOOT descriptor is wrong length (%d)\n", + printk (KERN_WARNING "SBF: ACPI BOOT descriptor is wrong length (%d)\n", sb.sbf_len); sbf_port = sb.sbf_cmos; /* Save CMOS port */ @@ -81,61 +88,65 @@ static void __init sbf_write(u8 v) { + unsigned long flags; + if(sbf_port != -1) { - v &= ~(1<<7); + v &= ~SBF_PARITY; if(!parity(v)) - v|=1<<7; + v|=SBF_PARITY; /* Make parity odd */ - spin_lock(&rtc_lock); + printk(KERN_INFO "SBF: Setting boot flags 0x%x\n",v); + + spin_lock_irqsave(&rtc_lock, flags); CMOS_WRITE(v, sbf_port); - spin_unlock(&rtc_lock); + spin_unlock_irqrestore(&rtc_lock, flags); } } static u8 __init sbf_read(void) { u8 v; + unsigned long flags; + if(sbf_port == -1) return 0; - spin_lock(&rtc_lock); + spin_lock_irqsave(&rtc_lock, flags); v = CMOS_READ(sbf_port); - spin_unlock(&rtc_lock); + spin_unlock_irqrestore(&rtc_lock, flags); return v; } static int __init sbf_value_valid(u8 v) { - if(v&0x78) /* Reserved bits */ + if(v&SBF_RESERVED) /* Reserved bits should be 0 */ return 0; if(!parity(v)) return 0; return 1; } - static void __init sbf_bootup(void) { u8 v = sbf_read(); if(!sbf_value_valid(v)) - v = 0; -#if defined(CONFIG_PNPBIOS) - /* Tell the BIOS to fast init as we are a PnP OS */ - v |= (1<<0); /* Set PNPOS flag */ + printk(KERN_WARNING "SBF: Simple boot flag value 0x%x read from CMOS RAM was invalid\n",v); + + v &= ~SBF_RESERVED; + v &= ~SBF_BOOTING; +#if defined(CONFIG_SBF_DIAG) + v |= SBF_DIAG; +#else + v &= ~SBF_DIAG; +#endif +#if defined(CONFIG_SBF_PNPOS) + v |= SBF_PNPOS; +#else + v &= ~SBF_PNPOS; #endif - sbf_write(v); -} -#ifdef NOT_USED -void linux_booted_ok(void) -{ - u8 v = sbf_read(); - if(!sbf_value_valid(v)) - return; - v &= ~(1<<1); /* Clear BOOTING flag */ sbf_write(v); } -#endif /* NOT_USED */ static int __init sbf_init(void) { @@ -235,7 +246,7 @@ if(sbf_struct_valid(rp)) { /* Found the BOOT table and processed it */ - printk(KERN_INFO "Simple Boot Flag extension found and enabled.\n"); + printk(KERN_INFO "SBF: Simple Boot Flag extension found and enabled.\n"); } iounmap((void *)rp); } - 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/