Messages in this thread Patch in this message | | | From | Mateusz Jończyk <> | Subject | Re: Testers wanted: Atom netbooks with x86_64 disabled by BIOS | Date | Sat, 27 Mar 2021 22:13:22 +0100 |
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W dniu 27.03.2021 o 21:32, Mateusz Jończyk pisze: > 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).
I have made two mistakes: - I left commented out code, - I have commented out lines with '#'. The code compiled though.
Attaching corrected patch, please excuse me.
Greetings, Mateusz
Signed-off-by: Mateusz Jończyk <mat.jonczyk@o2.pl>
--- arch/x86/boot/compressed/head_64.S | 2 -- 1 file changed, 2 deletions(-)
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index e94874f4bbc1..a9f0415da7c2 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -111,8 +111,6 @@ SYM_FUNC_START(startup_32) leal rva(boot_stack_end)(%ebp), %esp call verify_cpu - testl %eax, %eax - jnz .Lno_longmode /* * Compute the delta between where we were compiled to run at -- 2.25.1
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