parisc: Detect QEMU earlier in boot process

commit d006e95b5561f708d0385e9677ffe2c46f2ae345 upstream.

While adding LASI support to QEMU, I noticed that the QEMU detection in
the kernel happens much too late. For example, when a LASI chip is found
by the kernel, it registers the LASI LED driver as well.  But when we
run on QEMU it makes sense to avoid spending unnecessary CPU cycles, so
we need to access the running_on_QEMU flag earlier than before.

This patch now makes the QEMU detection the fist task of the Linux
kernel by moving it to where the kernel enters the C-coding.

Fixes: 310d82784fb4 ("parisc: qemu idle sleep support")
Signed-off-by: Helge Deller <deller@gmx.de>
Cc: stable@vger.kernel.org # v4.14+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c
index c3a532abac03951cf028017a58a0dc4dab5e1a4b..2e5216c28bb1a4badae86e5a1bf208421ee55f76 100644 (file)
--- a/arch/parisc/kernel/process.c
+++ b/arch/parisc/kernel/process.c
@@ -206,12 +206,6 @@ void __cpuidle arch_cpu_idle(void)
 
 static int __init parisc_idle_init(void)
 {
-       const char *marker;
-
-       /* check QEMU/SeaBIOS marker in PAGE0 */
-       marker = (char *) &PAGE0->pad0;
-       running_on_qemu = (memcmp(marker, "SeaBIOS", 8) == 0);
-
        if (!running_on_qemu)
                cpu_idle_poll_ctrl(1);
 

diff --git a/arch/parisc/kernel/setup.c b/arch/parisc/kernel/setup.c
index 2e66a887788e8781bf76b13cbd3fed02e6979259..581b0c66e521bf83d107221bc7cce4182cf93ec1 100644 (file)
--- a/arch/parisc/kernel/setup.c
+++ b/arch/parisc/kernel/setup.c
@@ -403,6 +403,9 @@ void start_parisc(void)
        int ret, cpunum;
        struct pdc_coproc_cfg coproc_cfg;
 
+       /* check QEMU/SeaBIOS marker in PAGE0 */
+       running_on_qemu = (memcmp(&PAGE0->pad0, "SeaBIOS", 8) == 0);
+
        cpunum = smp_processor_id();
 
        set_firmware_width_unlocked();