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 eb39e7e380d7e27b24f6bae39ae0e6c3583511e3..841db71958cdb50dff183dd058a9b09a5ec81421 100644 (file)
--- a/arch/parisc/kernel/process.c
+++ b/arch/parisc/kernel/process.c
@@ -210,12 +210,6 @@ 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 f2cf86ac279b4c52d93b67cfa395d0b08ee159a6..25946624ce6a47ed6c2854b5da9afdaead209718 100644 (file)
--- a/arch/parisc/kernel/setup.c
+++ b/arch/parisc/kernel/setup.c
@@ -396,6 +396,9 @@ void __init 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();
 
        init_cpu_topology();