uefi on newer board fail

[limcm12]

The iso rename cdrom is win11 installation disk about 6GB.
title cdrom memory top cdrom
find --set-root /cdrom.iso | set x=
echo x=%x%
map --mem --top %x%/cdrom.iso (0xff)
map --hook
root (0xff)
chainloader (0xff)

Grub4dos-for_UEFI-2025-08-14
As above tested on z97 with 32gb ram and z270 with 64gb ram in uefi with csm disable in bios and fully working.

Same ssd connected to b550m board with 64gb ram or x570 board with 64gb ram in uefi, Error 25 Disk read error.
With above secure boot disable, resize bar disable.
If use iso less than 1gb no problem copying to ram.

Grub4dos-0.4.6a-2025-08-12
Use grub4dos in csm mode, can copy the vhd(about 40gb) to ram there boot from ram.

[cdlt]

@limcm12 , I have the same problem. I have a motherboard based on the X570 chipset, and when copying a 24 GB static VHD to RAM with "map --mem --top hd(0,3)/1.vhd (hd)" in the latest version, it fails. It does not fail in the February 23, 2023 version. Have you found a way to make it work in the latest version for that chipset? From what you’re saying, it seems there is some issue with X570 motherboards when using newer versions of grub4dos for EFI.

[limcm12]

@cdltI, tested various version of grub4dos uefi the result as follow
On GPT SSd, 42gb windows11 static vhd to ram and there boot from ram

title win11pro.vhd mem top
find --set-root /win11pro.vhd | set x=
echo x=%x%
map --mem --top %x%/win11pro.vhd (hd)
chainloader (hd-1)

grub4dos-for_UEFI-2024-12-16
grub4dos-for_UEFI-2025-03-25
grub4dos-for_UEFI-2024-09-01
above version not working---error 25

below version working
grub4dos-for_UEFI-2023-11-29
grub4dos-for_UEFI-2024-02-26

Bios setting for asus x870
Above 4g decoding ENABLE
Resize bar support ENABLE
Secure boot OTHER

I have a msi x570 board, just try out the working grubefi version to see if it work.