Ventoy只能启动U盘上的ISO,我需要直接直接从硬盘上启动。
试了几天,终于发现了问题: iso-scan/filename 是必须的,Deepin Live 必须使用 findiso,其他又不能用!
编辑 /etc/grub.d/40_custom,末尾增加,保存后,sudo update-grub。

这些成功启动,但是有些丢失了选择菜单:
menuentry "Android_x86_64_8.1r5" {
set root=(hd0,5)
set isofile="/ISO/android-x86_64-8.1-r5.iso"
loopback loop $isofile
linux (loop)/kernel iso-scan/filename=$isofile
initrd (loop)/initrd.img
}

menuentry "Ubuntu Kylin" {
set root=(hd0,5)

set isofile="/ISO/ubuntukylin-20.04.1-enhanced-amd64.iso"

loopback loop $isofile

linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$isofile locale=zh_CN

initrd (loop)/casper/initrd

}

menuentry "ubuntu 16" {
set isofile="/ISO/ubuntu-16.04.7-desktop-amd64.iso"

loopback loop (hd0,5)$isofile

linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$isofile locale=zh_CN

initrd (loop)/casper/initrd

}

menuentry "KDE neon" {
set root=(hd0,5)

set isofile="/ISO/KDE-neon-user-20210217-1639.iso"

loopback loop $isofile

linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$isofile locale=zh_CN

initrd (loop)/casper/initrd

}

menuentry "Deepin Live" {
set root=(hd0,5)

set isofile="/ISO/deepin-live-system-2.0-amd64.iso"

loopback loop $isofile

linux (loop)/live/vmlinuz boot=live findiso=$isofile locale=zh_CN

initrd (loop)/live/initrd.img

}

menuentry "fossapup" {
set root=(hd0,5)

set isofile="/ISO/fossapup64-9.5.iso"

loopback loop $isofile

linux (loop)/vmlinuz iso-scan/filename=$isofile

initrd (loop)/initrd.gz

}

menuentry "slitaz" {
echo "Loading memdisk..."

linux16 /usr/lib/syslinux/memdisk iso raw

echo "Loading ISO..."

initrd16 /usr/slitaz-rolling.iso

}

menuentry "WIN7PE" {
echo "Loading memdisk..."

linux /usr/lib/syslinux/memdisk iso raw

echo "Loading ISO..."

initrd (hd0,5)/ISO/WIN7PE.iso

}

这些仍然失败:
menuentry "elementaryos" {
set root=(hd0,5)

set isofile="/ISO/elementaryos-5.1-stable.20200814.iso"

loopback loop $isofile

linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$isofile

initrd (loop)/casper/initrd.lz

}

menuentry "TinyCore" {
set root=(hd0,5)

set isofile="/ISO/CorePlus-current.iso"

loopback loop $isofile

linux (loop)/boot/vmlinuz boot=boot iso-scan/filename=$isofile

initrd (loop)/boot/core.gz

}