Before the new real-mode code infrastructure %edx was used for testing CD and NW bits with andl in order to decide whether to flush the processor caches or not. The value of cr0 was also stored in %eax, which was later used to set cr0 after masking out lower byte (except TS bit) in order to enter real-mode. In the new real-mode code infrastructure we wanted to keep input parameter in %eax so we are using %edx for both cr0 cases. This has caused regression since andl overwrites the value of %edx. This patch fixes the issue by replacing andl with testl, which is essentially andl without writing result to the register. Special thanks to Paolo Bonzini for noting this and proposing a fix. Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxx> --- arch/x86/realmode/rm/reboot_32.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/realmode/rm/reboot_32.S b/arch/x86/realmode/rm/reboot_32.S index 8d9bfd1..1140448 100644 --- a/arch/x86/realmode/rm/reboot_32.S +++ b/arch/x86/realmode/rm/reboot_32.S @@ -76,7 +76,7 @@ machine_real_restart_asm16: movl %edx, %cr0 movl %ecx, %cr3 movl %cr0, %edx - andl $0x60000000, %edx /* If no cache bits -> no wbinvd */ + testl $0x60000000, %edx /* If no cache bits -> no wbinvd */ jz 2f wbinvd 2: -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
