[syslinux] Only 2.5G of RAM available then syslinux64.efi boots 32-bit linux 686-pae

[Patrick Masotta]

>>>
      From: Andrey Plankin via Syslinux <syslinux at zytor.com>
 To: syslinux at zytor.com 
 Sent: Friday, November 20, 2015 11:04 PM
 Subject: [syslinux] Only 2.5G of RAM available then syslinux64.efi boots 32-bit linux 686-pae
   
Hello,

I'm booting linux-3.16-686-pae kernel (32-bit) via syslinux.efi 64-bit version.
After boot linux sees only 2.5G of RAM while system has 32G installed.

If I boot the same kernel with GRUB64 efi instead of syslinux 
then amount of RAM available to linux is 32G.

Is this a bug or I'm missing something?

syslinux.cfg:

label live-686-pae
        menu label Linux (686-pae)
        menu default
        linux /live/vmlinuz
        initrd /live/initrd.img
        append boot=live config persistence username=user live-config.utc=no acpi_osi=Linux live-config.noautologin


Current git: e0be4d87135

Regards,
Andrey
<<<
1) I think this problem is not related to appended kernel variables.2) Syslinux allocates and free EFI memory before calling ExitBootServices()but even if SL forgets freeing memory I cannot belive SL ever allocates 32-2.5=29.5GB or so.Then the problem does not look like not released SL allocated memory...

Questions
1) If you boot the PAE kernel with syslinux32.efi do you see the same problem?
2) Have you tried booting in different PCs to rule out some FW related issue?
Debugging this is not simple but it can be done calling EFI_BOOT_SERVICES.GetMemoryMap()as soon as the syslinux64.efi runs and before calling ExitBootServices() 
then parsing the returned array of EFI_MEMORY_DESCRIPTORS we can see what's going on.
Best,Patrick