Confirmed affecting Samsung Galaxy Book2 (i7-1255U, Intel Iris Xe
Graphics, 16GB LPDDR4x / NP750XED-KC4SE).
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https://bugs.launchpad.net/bugs/1842320
Title:
Can't boot: "error: out of memory." immediately after the grub menu
Status in grub:
Unknown
Status in OEM Priority Project:
Triaged
Status in grub2-signed package in Ubuntu:
Confirmed
Status in initramfs-tools package in Ubuntu:
Confirmed
Status in linux package in Ubuntu:
Confirmed
Bug description:
[Impact]
* In some cases, if the users' initramfs grow bigger, then it'll
likely not be able to be loaded by grub2.
* Some real cases from OEM projects:
In many built-in 4k monitor laptops with nvidia drivers, the u-d-c
puts the nvidia*.ko to initramfs which grows the initramfs to ~120M.
Also the gfxpayload=auto will remain to use 4K resolution since it's
what EFI POST passed.
In this case, the grub isn't able to load initramfs because the
grub_memalign() won't be able to get suitable memory for the larger
file:
```
#0 grub_memalign (align=1, size=592214020) at ../../../grub-core/kern/mm.c:376
#1 0x000000007dd7b074 in grub_malloc (size=592214020) at ../../../grub-core/kern/mm.c:408
#2 0x000000007dd7a2c8 in grub_verifiers_open (io=0x7bc02d80, type=131076)
at ../../../grub-core/kern/verifiers.c:150
#3 0x000000007dd801d4 in grub_file_open (name=0x7bc02f00 "/boot/initrd.img-5.17.0-1011-oem",
type=131076) at ../../../grub-core/kern/file.c:121
#4 0x000000007bcd5a30 in ?? ()
#5 0x000000007fe21247 in ?? ()
#6 0x000000007bc030c8 in ?? ()
#7 0x000000017fe21238 in ?? ()
#8 0x000000007bcd5320 in ?? ()
#9 0x000000007fe21250 in ?? ()
#10 0x0000000000000000 in ?? ()
```
Based on grub_mm_dump, we can see the memory fragment (some parts seem
likely be used because of 4K resolution?) and doesn't have available
contiguous memory for larger file as:
```
grub_real_malloc(...)
...
if (cur->size >= n + extra)
```
Based on UEFI Specification Section 7.2[1] and UEFI driver writers'
guide 4.2.3[2], we can ask 32bits+ on AllocatePages().
As most X86_64 platforms should support 64 bits addressing, we should
extend GRUB_EFI_MAX_USABLE_ADDRESS to 64 bits to get more available
memory.
* When users grown the initramfs, then probably will get initramfs
not found which really annoyed and impact the user experience (system
not able to boot).
[Test Plan]
* detailed instructions how to reproduce the bug:
1. Any method to grow the initramfs, such as install nvidia-driver.
2. If developers would like to reproduce, then could dd if=/dev/random
of=... bs=1M count=500, something like:
```
$ cat /usr/share/initramfs-tools/hooks/zzz-touch-a-file
#!/bin/sh
PREREQ=""
prereqs()
{
echo "$PREREQ"
}
case $1 in
# get pre-requisites
prereqs)
prereqs
exit 0
;;
esac
. /usr/share/initramfs-tools/hook-functions
dd if=/dev/random of=${DESTDIR}/test-500M bs=1M count=500
```
And then update-initramfs
* After applying my patches, the issue is gone.
* I did also test my test grubx64.efi in:
1. X86_64 qemu with
1.1. 60M initramfs + 5.15.0-37-generic kernel
1.2. 565M initramfs + 5.17.0-1011-oem kernel
2. Amd64 HP mobile workstation with
2.1. 65M initramfs + 5.15.0-39-generic kernel
2.2. 771M initramfs + 5.17.0-1011-oem kernel
All working well.
[Where problems could occur]
* The changes almost in i386/efi, thus the impact will be in the i386 / x86_64 EFI system.
The other change is to modify the "grub-core/kern/efi/mm.c" but I use the original addressing for "arm/arm64/ia64/riscv32/riscv64".
Thus it should not impact them.
* There is a "#if defined(__x86_64__)" which intent to limit the >
32bits code in i386 system and also
```
#if defined (__code_model_large__)
-#define GRUB_EFI_MAX_USABLE_ADDRESS 0xffffffff
+#define GRUB_EFI_MAX_USABLE_ADDRESS __UINTPTR_MAX__
+#define GRUB_EFI_MAX_ALLOCATION_ADDRESS 0x7fffffff
#else
#define GRUB_EFI_MAX_USABLE_ADDRESS 0x7fffffff
+#define GRUB_EFI_MAX_ALLOCATION_ADDRESS 0x3fffffff
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