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Diffstat (limited to 'system/memtest86+/patches/bug_629506_message_15.mbox')
| -rw-r--r-- | system/memtest86+/patches/bug_629506_message_15.mbox | 142 |
1 files changed, 0 insertions, 142 deletions
diff --git a/system/memtest86+/patches/bug_629506_message_15.mbox b/system/memtest86+/patches/bug_629506_message_15.mbox deleted file mode 100644 index 0b9362728f..0000000000 --- a/system/memtest86+/patches/bug_629506_message_15.mbox +++ /dev/null @@ -1,142 +0,0 @@ -From viro@ftp.linux.org.uk Fri Feb 27 20:21:34 2015 -Received: (at 629506) by bugs.debian.org; 27 Feb 2015 20:21:34 +0000 -X-Spam-Checker-Version: SpamAssassin 3.4.0-bugs.debian.org_2005_01_02 - (2014-02-07) on buxtehude.debian.org -X-Spam-Level: -X-Spam-Status: No, score=-2.3 required=4.0 tests=BAYES_00,FOURLA,MONEY, - MURPHY_DRUGS_REL8,RCVD_IN_DNSWL_MED,STOCKLIKE,T_RP_MATCHES_RCVD autolearn=no - autolearn_force=no version=3.4.0-bugs.debian.org_2005_01_02 -X-Spam-Bayes: score:0.0000 Tokens: new, 43; hammy, 150; neutral, 234; spammy, - 0. spammytokens: hammytokens:0.000-+--UD:patch, 0.000-+--H*u:1.5.21, - 0.000-+--H*UA:1.5.21, 0.000-+--H*u:2010-09-15, 0.000-+--H*UA:2010-09-15 -Return-path: <viro@ftp.linux.org.uk> -Received: from zeniv.linux.org.uk ([195.92.253.2]) - by buxtehude.debian.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:256) - (Exim 4.80) - (envelope-from <viro@ftp.linux.org.uk>) - id 1YRRPi-0007QW-72 - for 629506@bugs.debian.org; Fri, 27 Feb 2015 20:21:34 +0000 -Received: from viro by ZenIV.linux.org.uk with local (Exim 4.76 #1 (Red Hat Linux)) - id 1YRQyr-0000Hl-OS - for 629506@bugs.debian.org; Fri, 27 Feb 2015 19:53:49 +0000 -Date: Fri, 27 Feb 2015 19:53:49 +0000 -From: Al Viro <viro@ZenIV.linux.org.uk> -To: 629506@bugs.debian.org -Subject: memtest86+.bin crashes if loader ends up putting it not at 9000:0000 -Message-ID: <20150227195349.GN29656@ZenIV.linux.org.uk> -MIME-Version: 1.0 -Content-Type: text/plain; charset=us-ascii -Content-Disposition: inline -User-Agent: Mutt/1.5.21 (2010-09-15) -Sender: Al Viro <viro@ftp.linux.org.uk> -X-Greylist: delayed 1658 seconds by postgrey-1.34 at buxtehude; Fri, 27 Feb 2015 20:21:33 UTC - - FWIW, the effects described in this bug report are 100% reproducible -on any version, as long as the loader (lilo, grub, whatever) ends up putting -the bootsect+setup in any location below 9000:0000. - - zImage-type images consist of 3 parts - bootsect, setup and -payload. Payload is loaded at 1000:0, bootsect and setup - n:0 and -n+2:0 resp., near the top of lowmem. Payload is protected mode code, -setup - real mode one. Bootsect isn't executed at all; when the -same image is booted directly it would've been the only part loaded -by BIOS and it would copy itself and read the rest of the image to -expected locations and pass control to setup. Values in it can be -used by setup, though, so it must be present even when the image had been -brought in by a loader. - - The thing is, we can't be guaranteed n == 0x9000. E.g. ACPI and -SMM have every right to use _anything_ in range 512K..1M for their -state, declaring it reserved. That's what BIOS int 0x12 is for - it -reports how high (in kilobytes) can you go in lowmem without running into -reserved areas. And while having it report 512K is rare, something like -20K reserved just below the VRAM (i.e. report 620K) is nothing unusual. - - I hadn't looked into details of GRUB behaviour, but LILO puts its -secondary loader as high in lowmem as it can, then puts the bootsect and -setup parts of image below that. It tries to load at 9000:0 if possible, -but if there's no space, it'll go lower. With the sizes it uses 20K reserved -below 640K is enough to push bootsect + setup combination (just) below 9000:0. -And memtest86+ setup has that 0x9000 hardwired - this -gdt_48: - .word 0x800 # gdt limit=2048, 256 GDT entries - .word 512+gdt - start,0x9 # gdt base = 0X9xxxx -in setup.S really depends on 'start' (entry to setup) loaded at -0x90200 physical. Have it loaded at any other address and you'll trigger -an exception as soon as you try to assign any segment register after you switch -to protected mode. Which will escalate to triple-fault and reboot the -damn thing immediately. - - GRUB might be better or worse in triggering that "load not at -9000:0" situation, but it can't possibly avoid it in all cases. If nothing -else, 9000:0 might be within one of the reserved areas. It simply isn't -guaranteed to be available, period. - - Another issue is that setup of memtest86+ expects to see in %dx -the value left there by the bootsect of memtest86+. Fortunately, it's -not critical - in - movw $INITSEG, %ax - movw %ax, %ds - movw %ax, %es - movw %ax, %fs - movw %ax, %ss # reset the stack to INITSEG:0x4000-12. - movw %dx, %sp - push %cs - pop %ds -we really need only the last two instructions. The stack footprint -of what follows is fairly low *and* these values are not used past the -reload of segment registers immediately after protected mode switch. - -It's not the only problem in there - the bits after -# start from grub-a20.patch -are clearly cargo-culted from grub, badly. There it was a part of a function -that expects an argument on stack (it can turn A20 both on and off) and that -got blindly copied, nevermind that the value on stack is random or that -we follow it with (unconditional) use of 8042-based method anyway. I'd rather -see upstream opinion on that particular piece of code first, though. - -Anyway, the patch below fixes dependency on being loaded at 9000:0 and it -seems to work here without regressions. Have fun... - ---- memtest86+-5.01/setup.S 2013-08-09 22:01:58.000000000 -0400 -+++ fixed/setup.S 2015-02-27 14:18:47.000000000 -0500 -@@ -26,14 +26,13 @@ - # APs also execute this code - #ljmp $INITSEG, $(reload - start + 0x200) - reload: -- movw $INITSEG, %ax -- movw %ax, %ds -- movw %ax, %es -- movw %ax, %fs -- movw %ax, %ss # reset the stack to INITSEG:0x4000-12. -- movw %dx, %sp -+ xorl %eax, %eax - push %cs -- pop %ds -+ pop %ax -+ movw %ax, %ds -+ shll $4, %eax -+ addl %eax, (gdt_48 - start + 2) -+ - lidt idt_48 - start # load idt with 0,0 - lgdt gdt_48 - start # load gdt with whatever appropriate - -@@ -88,6 +87,7 @@ - movw %ax, %ds - movw %ax, %es - movw %ax, %ss -+ xorl %esp, %esp # 32bit code will set it then - movw %ax, %fs - movw %ax, %gs - -@@ -144,7 +144,7 @@ - - gdt_48: - .word 0x800 # gdt limit=2048, 256 GDT entries -- .word 512+gdt - start,0x9 # gdt base = 0X9xxxx -+ .word gdt - start,0 # gdt base, needs to be adjusted - - msg1: - .asciz "Setup.S\r\n" - - |