Syslinux - Nov 2013 - Sysinux 6 will not boot ISOs on BIOS (i.e. pre-UEFI) systems

On 11/25/2013 04:12 PM, Gerardo Exequiel Pozzi wrote:
> 
> I made some more and more experiments beyond LBA 65535
> 
> Works: * isolinux-4.07.bin (size 24574) * isolinux-5.00.bin (size
> 34816)
> 
> Does not work: * isolinux-5.01.bin (size 34816) * isolinux-5.10.bin
> (size 36864) * isolinux-6.00.bin (size 38912) * isolinux-6.02.bin
> (size 43008)
> 
> * I just tested exactly at LBA 65535 (works all versions) and LBA
> 65536 (fails all versions > 5.00).
> 
What the heck... there are just about zero plausible differences
between 5.00 and 5.01.

I'm wondering if 17a36e2c91706512e6c425222c9a9a451d9db854 could
plausibly have anything to do with this, since that seems to be the
only possible patch that might affect isolinux.  Is there any way you
could try 5.01-pre1 and 5.01-pre2?  If -pre1 works and -pre2 doesn't,
it is likely that the problem lies in that commit.

	-hpa

On 11/25/2013 06:32 PM, H. Peter Anvin wrote:
> On 11/25/2013 04:12 PM, Gerardo Exequiel Pozzi wrote:
>>
>> I made some more and more experiments beyond LBA 65535
>>
>> Works: * isolinux-4.07.bin (size 24574) * isolinux-5.00.bin (size
>> 34816)
>>
>> Does not work: * isolinux-5.01.bin (size 34816) * isolinux-5.10.bin
>> (size 36864) * isolinux-6.00.bin (size 38912) * isolinux-6.02.bin
>> (size 43008)
>>
>> * I just tested exactly at LBA 65535 (works all versions) and LBA
>> 65536 (fails all versions > 5.00).
>>
> 
> What the heck... there are just about zero plausible differences
> between 5.00 and 5.01.
> 
> I'm wondering if 17a36e2c91706512e6c425222c9a9a451d9db854 could
> plausibly have anything to do with this, since that seems to be the
> only possible patch that might affect isolinux.  Is there any way you
> could try 5.01-pre1 and 5.01-pre2?  If -pre1 works and -pre2 doesn't,
> it is likely that the problem lies in that commit.
> 
If you have the ability to rebuild Syslinux from source, perhaps you
could try the following patch?

	-hpa


-------------- next part --------------
diff --git a/core/isolinux.asm b/core/isolinux.asm
index bd4e9556922d..c4db4133e274 100644
--- a/core/isolinux.asm
+++ b/core/isolinux.asm
@@ -420,7 +420,7 @@ MaxLMA		equ 384*1024		; Reasonable limit (384K)
 		call getlinsec
 		pop eax
 		pop cx
-		mov dx,cx
+		movzx edx,cx
 		pop bp
 		pop bx

On 11/26/2013 01:14 AM, H. Peter Anvin wrote:
> On 11/25/2013 06:32 PM, H. Peter Anvin wrote:
>> On 11/25/2013 04:12 PM, Gerardo Exequiel Pozzi wrote:
>>>
>>> I made some more and more experiments beyond LBA 65535
>>>
>>> Works: * isolinux-4.07.bin (size 24574) * isolinux-5.00.bin (size
>>> 34816)
>>>
>>> Does not work: * isolinux-5.01.bin (size 34816) * isolinux-5.10.bin
>>> (size 36864) * isolinux-6.00.bin (size 38912) * isolinux-6.02.bin
>>> (size 43008)
>>>
>>> * I just tested exactly at LBA 65535 (works all versions) and LBA
>>> 65536 (fails all versions > 5.00).
>>>
>>
>> What the heck... there are just about zero plausible differences
>> between 5.00 and 5.01.
>>
>> I'm wondering if 17a36e2c91706512e6c425222c9a9a451d9db854 could
>> plausibly have anything to do with this, since that seems to be the
>> only possible patch that might affect isolinux.  Is there any way you
>> could try 5.01-pre1 and 5.01-pre2?  If -pre1 works and -pre2
doesn't,
>> it is likely that the problem lies in that commit.
>>
Yes this is the offending commit as I said in the previous message
[#1](*) reverting fixes it.
> 
> If you have the ability to rebuild Syslinux from source, perhaps you
> could try the following patch?
Yes. I done the rebuild, but I can not test just now (enconding video!).
I will post the result in ~10 hours ;)

If anyone that can reproduce the issue want to test, here is the
compressed (~167K) ISO image (~129M)[#2].
This is just and ISO image with isolinux.bin (at LBA 65536) patched +
"coco" (a file filled with \0), so if works propertly, you can see
message about missing ldlinux.c32.


Thanks for your time!


[#1] http://www.syslinux.org/archives/2013-November/021187.html
[#2]
https://dl.dropboxusercontent.com/u/88891866/test-isolinux-6.02.patched.iso.gz

https://dl.dropboxusercontent.com/u/88891866/test-isolinux-6.02.patched.iso.gz.sha1



(*) PS: Why messages sent to syslinux mailing-list takes too longer time
to become available (I am registered)?

-- 
Gerardo Exequiel Pozzi
\cos^2\alpha + \sin^2\alpha = 1

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-----Original Message-----
From: Syslinux [mailto:syslinux-bounces at zytor.com] On Behalf Of H. Peter
Anvin
Sent: Tuesday, November 26, 2013 7:15 AM
To: For discussion of Syslinux and tftp-hpa
Subject: Re: [syslinux] Sysinux 6 will not boot ISOs on BIOS (i.e. pre-UEFI)
systems

On 11/25/2013 06:32 PM, H. Peter Anvin wrote:
> On 11/25/2013 04:12 PM, Gerardo Exequiel Pozzi wrote:
>>
>> I made some more and more experiments beyond LBA 65535
>>
>> Works: * isolinux-4.07.bin (size 24574) * isolinux-5.00.bin (size
>> 34816)
>>
>> Does not work: * isolinux-5.01.bin (size 34816) * isolinux-5.10.bin 
>> (size 36864) * isolinux-6.00.bin (size 38912) * isolinux-6.02.bin 
>> (size 43008)
>>
>> * I just tested exactly at LBA 65535 (works all versions) and LBA
>> 65536 (fails all versions > 5.00).
>>
> 
> What the heck... there are just about zero plausible differences 
> between 5.00 and 5.01.
> 
> I'm wondering if 17a36e2c91706512e6c425222c9a9a451d9db854 could 
> plausibly have anything to do with this, since that seems to be the 
> only possible patch that might affect isolinux.  Is there any way you 
> could try 5.01-pre1 and 5.01-pre2?  If -pre1 works and -pre2 doesn't, 
> it is likely that the problem lies in that commit.
> 
If you have the ability to rebuild Syslinux from source, perhaps you could
try the following patch?

	-hpa