Syslinux - Aug 2015 - [PATCH] efi: leaving long mode in kernel_jump routine

>>>
 > Syslinux 6.03 (efi64) fails to boot a 32-bit kernel. The way Syslinux
 > leaves long mode in kernel_jump assembly routine does not follow AMD64
 > specifications. More precisely:
 > 1. After setting a new GADT, `cs` has to be refresh by doing a long
 > jump, but it is not
 > 2. Other segments have to be updated, but they are not
 > 3. Disabling paging has to be done before disabling long mode, but the
 > implementation does the opposite
 > 
 > In most cases,  computer that tries to execute the kernel_jump routine
 > reboot (it can also hangs). This patch fixes the kernel_jump routine.
 > 
  
 Is this patch going to be yet another one that will be "lost" in the 
mailing list?
 Is this patch incorrect? Not useful? Unnecessary?
<<<
It seems "it is" necessary, I'll be probably testing it next week.
>>> 
 Newer kernels are supposed to respect certain rules / standards / 
 protocols, and IF everything is done "adequately", then Syslinux
(BIOS
 / EFI*) should be able to boot such newish kernels.
<<<

AFAIK it seems this patch is even necessary for new kernels in  the case
EFI64 boots a 32 Bit kernel, right?
 
Best,
Patrick

Hi!
Sorry for not responding earlier. I was planning to but I lack time.
> AFAIK it seems this patch is even necessary for new kernels in  the case
> EFI64 boots a 32 Bit kernel, right?
I think it is, yes. I will try to do more test myself. I hope I will be
able to tell more this week.

>>> 
 > AFAIK it seems this patch is even necessary for new kernels in? the case
 > EFI64 boots a 32 Bit kernel, right?
 
 I think it is, yes. I will try to do more test myself. I
 hope I will be  able to tell more this week.
Thomas Letan
 <<<

Whenever you get a minute please let us know.
Thanks ;-)

Best,
Patrick