[syslinux] PXELINUX LocalBoot 0 fail; hunting for bug

Gene Cumm gene.cumm at gmail.com
Mon Aug 9 13:56:13 PDT 2010


On Sat, Aug 7, 2010 at 20:36, H. Peter Anvin <hpa at zytor.com> wrote:
> On 08/07/2010 10:45 AM, Gene Cumm wrote:
>> Recently, I decided to pull out a new model laptop for testing related
>> to my job at work.  Dell Latitiude E6400, BIOS A14.  Normally I have
>> it set to boot CD, USB, Net, then HDD and noticed that with
>> PXELINUX-4.02 and 'LOCALBOOT 0', it hung on me before leaving the PXE
>> stack.  I then tried 3.86 and it worked.  4.00 and 4.01 both hung when
>> I tested them as well.  Changing to 'LOCALBOOT -1' or using 'chain.c32
>> hd0' both resolved this issue.
>>
>> At this time, I'm just trying to post to give people an FYI in case
>> they run into a similar situation and to say that I'm going to be
>> trying to hunt for where/how things are hanging.
>>
>> I still have to get another test environment configured to obtain the
>> exact displayed messages.
>>
>
> It's always worth trying a "git bisect" if you can.
>
>        -hpa

4.00-pre2 failed the same way and -pre1 looks like it messed up the
config file.  "TFTP server sent an incomprehensible reply"

Messages:

"Booting from local disk..." happens in both versions 4.02 and 3.86.
"PXE-M0F: Exiting Intel Boot Agent." happens only in 3.86 or with
something other than 'LOCALBOOT 0'.

Attempting to load 4.02 first then 3.86 from there also results in the issue.

bisecting away yields this as the bad commit.

410c91f5624370b1b6a7575d2049db62e6946eeb is the first bad commit
commit 410c91f5624370b1b6a7575d2049db62e6946eeb
Author: H. Peter Anvin <hpa at zytor.com>
Date:   Thu May 14 11:59:46 2009 -0700

    First cut of doing 32-bit C code in the core

    A very preliminary implementation of 32-bit C code in the core.  This
    currently breaks ADV, because the installer assumes the ADV is the
    last two sectors in extlinux.sys -- need to figure out a way to deal
    with this hopefully without breaking the migration protocol.

    Signed-off-by: H. Peter Anvin <hpa at zytor.com>

:040000 040000 eb1ca192a7ad0e088950977b57ec06faa9ce4317
25962fa7c8f628a6628e75e742495cff586277f9 M      core

BIOS versions A14, A20 and A25 are all affected.  Depending on the
version of PXELINUX, pressing Ctrl-Alt-Del has mixed results (either
no response or perfect response).  4.02 works perfectly for
Ctrl-Alt-Del.

-- 
-Gene




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