Re: [PATCH 1/1] x86/power: only verify usable RAM regions during hibernation E820 check

Hello Rafael. OK, what is proper solution for the Hibernate inconsistent 
memory map detected! problem?

Thank you,

best regards,

Milan Oravec

CIKT UKF Nitra
Mobil/Signal: +421907670270
email: [email protected]

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Tuto spravu nepreveril ziadny antivirus - nebolo treba...

On 6/23/26 14:59, Rafael J. Wysocki wrote:
> On Sat, Jun 20, 2026 at 10:16 AM Marco Scardovi <[email protected]> wrote:
>> On some UEFI platforms (such as the HP OmniBook X Flip), resuming from
>> hibernation fails with 'Hibernate inconsistent memory map detected!'
>> even though the usable system RAM configuration is identical.
> That may not be sufficient for the image kernel to work after resuming though.
>
>> This happens because the UEFI firmware or bootloader (like GRUB) makes
>> non-deterministic allocations or shifts reserved/ACPI memory regions
>> dynamically across boots,
> The boot loader has nothing to do with this, the memory map comes from
> the UEFI firmware.
>
>> which changes the CRC32 checksum computed
>> over the entire E820 table (which includes non-RAM types like reserved,
>> ACPI, NVS, and unusable memory).
>>
>> Fix this by modifying compute_e820_crc32() to only calculate the
>> checksum over memory map entries of type E820_TYPE_RAM. Usable system
>> RAM layout is still verified to ensure data safety, but dynamic shifts
>> in ACPI and other reserved ranges are ignored.
> Which is risky because the image kernel may access stuff located in
> those non-RAM memory regions (for instance, ACPI tables, AML operation
> regions, UEFI runtime variables, etc.).
>
> Hibernation in Linux simply cannot cope with a changing memory map in
> general, sorry about that.
>
>> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221569
>> Fixes: f5d1499ae209 ("PM: hibernate: x86: Use crc32 instead of md5 for hibernation e820 integrity check")
>> Assisted-by: Antigravity:gemini-3.5-flash
>> Signed-off-by: Marco Scardovi <[email protected]>
>> ---
>>   arch/x86/power/hibernate.c | 15 +++++++++++----
>>   1 file changed, 11 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/x86/power/hibernate.c b/arch/x86/power/hibernate.c
>> index a2294c1649f6..752a490bc3d2 100644
>> --- a/arch/x86/power/hibernate.c
>> +++ b/arch/x86/power/hibernate.c
>> @@ -70,12 +70,19 @@ struct restore_data_record {
>>    *
>>    * Return: the resulting checksum
>>    */
>> -static inline u32 compute_e820_crc32(struct e820_table *table)
>> +static u32 compute_e820_crc32(struct e820_table *table)
>>   {
>> -       int size = offsetof(struct e820_table, entries) +
>> -               sizeof(struct e820_entry) * table->nr_entries;
>> +       u32 crc = ~0;
>> +       int i;
>> +
>> +       for (i = 0; i < table->nr_entries; i++) {
>> +               if (table->entries[i].type == E820_TYPE_RAM) {
>> +                       crc = crc32_le(crc, (unsigned char const *)&table->entries[i],
>> +                                      sizeof(struct e820_entry));
>> +               }
>> +       }
>>
>> -       return ~crc32_le(~0, (unsigned char const *)table, size);
>> +       return ~crc;
>>   }
>>
>>   #ifdef CONFIG_X86_64
>> --
>> 2.54.0
>>
>>