Messages in this thread Patch in this message | | | From | Mateusz Jończyk <> | Subject | Testers wanted: Atom netbooks with x86_64 disabled by BIOS | Date | Sat, 27 Mar 2021 21:32:18 +0100 |
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Hello,
There are some netbooks with Intel Atom processors that have 64-bit support disabled by BIOS. Theoretically, the processor supports 64-bit operation, but BIOS allows only 32-bit code to run.
I wonder whether the 64-bit mode is really disabled in the CPU or only hidden in the CPUID flags. If the latter, the computer could be made to run a 64-bit kernel.
Similarly, there are some Pentium M processors that support PAE (Physical Address Extensions), but do not show this in CPUID. They could be made to run distributions that require PAE with the "forcepae" kernel command line parameter.
I would like to ask people with such netbooks to try to run a 64-bit kernel with this patch applied.
When a patched 64-bit kernel is run in `qemu-system-i386`, the virtual machine restarts instantly. Without this patch in such a case a 64-bit kernel hangs indefinitely (inside .Lno_longmode in head_64.S).
CC: Thomas Gleixner <tglx@linutronix.de> CC: Ingo Molnar <mingo@redhat.com> CC: Borislav Petkov <bp@alien8.de> CC: <x86@kernel.org>
Signed-off-by: Mateusz Jończyk <mat.jonczyk@o2.pl>
--- arch/x86/boot/compressed/head_64.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index e94874f4bbc1..23c376d0b221 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -112,7 +112,7 @@ SYM_FUNC_START(startup_32) call verify_cpu testl %eax, %eax - jnz .Lno_longmode + #jnz .Lno_longmode /* * Compute the delta between where we were compiled to run at -- 2.25.1
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