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armbian-kernel.sh: introduce KERNEL_BTF=no to opt-out of BTF/CO-RE type-info on low-RAM machines

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- turns out `pahole` for `vmlinux` can take multiple gigabytes of RAM to run successfully
- I can't simply decide based on available RAM, as that would make .config hashes mismatch
- thus, introduce:
  - default is to enable BTF; if on low-ram host, error out unless KERNEL_BTF=yes is passed
  - if KERNEL_BTF=no is passed, the BTF debug info is always disabled
  - if KERNEL_BTF=yes is passed, then a warning is produced, but BTF is still enabled
- the magic number "6451 MiB" was determined empirically (and is probably bs)
This commit is contained in:
Ricardo Pardini
2025-01-08 00:46:45 +01:00
committed by Igor
parent cb6f2fbef8
commit 51b300ebdf
1 changed files with 64 additions and 35 deletions
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101
lib/functions/compilation/armbian-kernel.sh
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@@ -57,51 +57,46 @@ function armbian_kernel_config__disable_various_options() {
fi
}
function armbian_kernel_config__600_enable_ebpf_and_btf_info() {
display_alert "Enabling eBPF and BTF info" "for fully BTF & CO-RE enabled kernel" "info"
function armbian_kernel_config__force_pa_va_48_bits_on_arm64() {
declare -A opts_val=()
declare -a opts_n=("CONFIG_DEBUG_INFO_NONE")
declare -a opts_y=(
"CONFIG_BPF_JIT" "CONFIG_BPF_JIT_DEFAULT_ON" "CONFIG_FTRACE_SYSCALLS" "CONFIG_PROBE_EVENTS_BTF_ARGS" "CONFIG_BPF_KPROBE_OVERRIDE"
"CONFIG_DEBUG_INFO" "CONFIG_DEBUG_INFO_DWARF5"
"CONFIG_DEBUG_INFO_BTF" "CONFIG_DEBUG_INFO_BTF_MODULES"
)
declare -a opts_y=() opts_n=()
if [[ "${ARCH}" == "arm64" ]]; then
opts_y+=("CONFIG_ARM64_VA_BITS_48")
opts_val["CONFIG_ARM64_PA_BITS"]="48"
fi
armbian_kernel_config_apply_opts_from_arrays
}
declare opt_y opt_val opt_n
for opt_n in "${opts_n[@]}"; do
kernel_config_modifying_hashes+=("${opt_n}=n")
done
function armbian_kernel_config__600_enable_ebpf_and_btf_info() {
declare -A opts_val=()
declare -a opts_y=() opts_n=()
for opt_y in "${opts_y[@]}"; do
kernel_config_modifying_hashes+=("${opt_y}=y")
done
if [[ "${KERNEL_BTF}" == "no" ]]; then # If user is explicit by passing "KERNEL_BTF=no", then actually disable all debug info.
display_alert "Disabling eBPF and BTF info for kernel" "as requested by KERNEL_BTF=no" "info"
opts_y+=("CONFIG_DEBUG_INFO_NONE") # Enable the "none" option
opts_n+=("CONFIG_DEBUG_INFO" "CONFIG_DEBUG_INFO_DWARF5" "CONFIG_DEBUG_INFO_BTF" "CONFIG_DEBUG_INFO_BTF_MODULES") # BTF & CO-RE == off
# We don't disable the eBPF options, as eBPF itself doesn't require BTF (debug info) and doesnt' consume as much memory during build as BTF debug info does.
else
declare -i available_physical_memory_mib
available_physical_memory_mib=$(($(awk '/MemAvailable/ {print $2}' /proc/meminfo) / 1024)) # MiB
display_alert "Considering available RAM for BTF build" "${available_physical_memory_mib} MiB" "info"
for opt_val in "${!opts_val[@]}"; do
kernel_config_modifying_hashes+=("${opt_val}=${opts_val[$opt_val]}")
done
if [[ -f .config ]]; then
for opt_n in "${opts_n[@]}"; do
display_alert "Disabling kernel opt" "${opt_n}=n" "debug"
kernel_config_set_n "${opt_n}"
done
for opt_y in "${opts_y[@]}"; do
display_alert "Enabling kernel opt" "${opt_y}=y" "debug"
kernel_config_set_y "${opt_y}"
done
for opt_val in "${!opts_val[@]}"; do
display_alert "Setting kernel opt" "${opt_val}=${opts_val[$opt_val]}" "debug"
kernel_config_set_val "${opt_val}" "${opts_val[$opt_val]}"
done
if [[ ${available_physical_memory_mib} -lt 6451 ]]; then # If less than 6451 MiB of RAM is available, then exit with an error, telling the user to avoid pain and set KERNEL_BTF=no ...
if [[ "${KERNEL_BTF}" == "yes" ]]; then # ... except if the user knows better, and has set KERNEL_BTF=yes, then we'll just warn.
display_alert "Not enough RAM available (${available_physical_memory_mib}Mib) for BTF build" "but KERNEL_BTF=yes is set; enabling BTF" "warn"
else
exit_with_error "Not enough RAM available (${available_physical_memory_mib}Mib) for BTF build. Please set 'KERNEL_BTF=no' to avoid running out of memory during the kernel LD/BTF build step; or ignore this check by setting 'KERNEL_BTF=yes' -- that might put a lot of load on your swap disk, if any."
fi
fi
display_alert "Enabling eBPF and BTF info" "for fully BTF & CO-RE enabled kernel" "info"
opts_n+=("CONFIG_DEBUG_INFO_NONE") # Make sure the "none" option is disabled
opts_y+=(
"CONFIG_BPF_JIT" "CONFIG_BPF_JIT_DEFAULT_ON" "CONFIG_FTRACE_SYSCALLS" "CONFIG_PROBE_EVENTS_BTF_ARGS" "CONFIG_BPF_KPROBE_OVERRIDE" # eBPF == on
"CONFIG_DEBUG_INFO" "CONFIG_DEBUG_INFO_DWARF5" "CONFIG_DEBUG_INFO_BTF" "CONFIG_DEBUG_INFO_BTF_MODULES" # BTF & CO-RE == off
)
fi
armbian_kernel_config_apply_opts_from_arrays
return 0
}
@@ -166,3 +161,37 @@ function kernel_config_set_val() {
display_alert "Setting kernel config/module value" "${config}=${value}" "debug"
run_host_command_logged ./scripts/config --set-val "${config}" "${value}"
}
# This takes opts_n, opts_y, arrays from parent scope; also the opts_val dictionary;
# it and applies them to the hashes and to the .config if it exists.
function armbian_kernel_config_apply_opts_from_arrays() {
declare opt_y opt_val opt_n
for opt_n in "${opts_n[@]}"; do
kernel_config_modifying_hashes+=("${opt_n}=n")
done
for opt_y in "${opts_y[@]}"; do
kernel_config_modifying_hashes+=("${opt_y}=y")
done
for opt_val in "${!opts_val[@]}"; do
kernel_config_modifying_hashes+=("${opt_val}=${opts_val[$opt_val]}")
done
if [[ -f .config ]]; then
for opt_n in "${opts_n[@]}"; do
display_alert "Disabling kernel opt" "${opt_n}=n" "debug"
kernel_config_set_n "${opt_n}"
done
for opt_y in "${opts_y[@]}"; do
display_alert "Enabling kernel opt" "${opt_y}=y" "debug"
kernel_config_set_y "${opt_y}"
done
for opt_val in "${!opts_val[@]}"; do
display_alert "Setting kernel opt" "${opt_val}=${opts_val[$opt_val]}" "debug"
kernel_config_set_val "${opt_val}" "${opts_val[$opt_val]}"
done
fi
}