[syslinux] Question about syslinux EFI alpha version

H. Peter Anvin hpa at zytor.com
Thu May 9 08:02:24 PDT 2013

On 05/09/2013 07:48 AM, Matt Fleming wrote:
> On Thu, 09 May, at 07:03:21AM, H. Peter Anvin wrote:
>> On 05/09/2013 05:51 AM, Matt Fleming wrote:
>>> Yeah, that could be a good idea. It would save us from having to invent
>>> a scheme to ensure we load the correct ldlinux.c32 depending on whether
>>> we're booting 32-bit or 64-bit.
>> The question is if we don't need that anyway for modules... after all,
>> every module, not just ldlinux.c32, is affected here.
>> Additionally, I do believe BIOS and EFI have different .c32 modules, no?
> Yes, the .c32 modules for BIOS, efi32 and efi64 are all different.
> Notably the BIOS and efi32 modules are compiled with different CFLAGS
> (the immediate thing that comes to mind is -mno-red-zone).

The redzone is an x86-64 ABI feature... -mno-red-zone should have no
effect.  I presume you meant -mregparm=3?

Either way, it is likely that low-level accesses will seep into modules,
so even if the ABIs are compatible it doesn't make much sense.

>> Unless they are in separate trees, I think we'll need separate names.
> Once ldlinux.c32 is loaded it can parse the PATH directive in a config
> file, which can be used to point to separate trees. Of course, you need
> to be able to load *different* config files for BIOS, efi32 and efi64,
> so that moves the problem rather than solving it.

Although we may end up doing something like macros for that (people are
asking for that) ... so it is worth thinking about it.


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