[syslinux] boot... round 2

Gene Cumm gene.cumm at gmail.com
Mon Jun 29 19:27:22 PDT 2015


On Mon, Jun 29, 2015 at 6:20 PM, poma via Syslinux <syslinux at zytor.com> wrote:
> On 29.06.2015 17:06, Matthew Miller via Syslinux wrote:
>
>>
>> It actuallly looks from Adam's investigation that this isn't different
>> for this package. So, less than certainly. It looks like maybe more a
>> gcc 5 difference.
>>
>>
>>
>
> Regardless of whatever is actually causing this,
> here is the isolinux-debug.bin output:
>
> Booting from DVD/CD...
>
> ISOLINUX 6.03   Copyright (C) 1994-2014 H. Peter Anvin et al
> isolinux: Starting up, DL = E0
> isolinux: Loaded spec packet OK, drive = E0
> isolinux: Main image LBA = 00000A12
> isolinux: Image read, jumping to main code...
> _
>
>
> Booting from DVD/CD...
>
> ISOLINUX 6.04   Copyright (C) 1994-2015 H. Peter Anvin et al
> isolinux: Starting up, DL = E0
> isolinux: Loaded spec packet OK, drive = E0
> isolinux: Main image LBA = 00000A12
> isolinux: Image read, jumping to main code...
> _
>

So most of the nasm code should be OK.

> If anyone has an idea how to debug this further,
> do not hesitate.
> Sooner or later all distros gonna hit this.

A real serial port that can reliably operate at 115200 8n1 may be
necessary.  Build logs help sometimes for new warnings.  Has anyone
attempted builds outside the .src.rpm files?

> syslinux-6.04-1.fc23.x86_64

I didn't expect to see that.  I incremented version solely to indicate
it's past 6.03.  6.04 hasn't even seen a pre-release yet (officially).
What commit ID is this?

> nasm-2.11.08-2.fc23.x86_64

Hopefully this is past the issues with 2.11.06 (and no other regressions).

> mtools-4.0.18-9.fc23.x86_64
> mingw64-gcc-5.1.0-3.fc23.x86_64
> libuuid-2.26.2-1.fc23.x86_64
> glibc-2.21.90-17.fc23.x86_64
> gcc-5.1.1-4.fc23.x86_64

What gcc is Fedora 21 on?  Fedora 22?  Why aren't we comparing Fedora
23's builds to Fedora 22 where there should be fewer differences?

The boot loader itself can't really be hardened in the same way as
typical runtime code under a kernel (such as Linux).  Remember, we
typically start in 16-bit real mode at address CS:IP 0x0000:0x7C00,
prepare an environment then switch to something more like protected
mode.  The boot loader _installers_ should be safe with the hardening.

-- 
-Gene


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