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The decompressor has a hard limit on the number of page tables it can
allocate. This limit is defined at compile-time and will cause boot
failure if it is reached.
The kernel is very strict and calculates the limit precisely for the
worst-case scenario based on the current configuration. However, it is
easy to forget to adjust the limit when a new use-case arises. The
worst-case scenario is rarely encountered during sanity checks.
In the case of enabling 5-level paging, a use-case was overlooked. The
limit needs to be increased by one to accommodate the additional level.
This oversight went unnoticed until Aaron attempted to run the kernel
via kexec with 5-level paging and unaccepted memory enabled.
Update wost-case calculations to include 5-level paging.
To address this issue, let's allocate some extra space for page tables.
128K should be sufficient for any use-case. The logic can be simplified
by using a single value for all kernel configurations.
[ Also add a warning, should this memory run low - by Dave Hansen. ]
Fixes:
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.. | ||
compressed | ||
tools | ||
.gitignore | ||
a20.c | ||
apm.c | ||
bioscall.S | ||
bitops.h | ||
boot.h | ||
cmdline.c | ||
copy.S | ||
cpu.c | ||
cpucheck.c | ||
cpuflags.c | ||
cpuflags.h | ||
ctype.h | ||
early_serial_console.c | ||
edd.c | ||
genimage.sh | ||
header.S | ||
install.sh | ||
io.h | ||
main.c | ||
Makefile | ||
memory.c | ||
mkcpustr.c | ||
msr.h | ||
mtools.conf.in | ||
pm.c | ||
pmjump.S | ||
printf.c | ||
regs.c | ||
setup.ld | ||
string.c | ||
string.h | ||
tty.c | ||
version.c | ||
vesa.h | ||
video-bios.c | ||
video-mode.c | ||
video-vesa.c | ||
video-vga.c | ||
video.c | ||
video.h |