parisc: Detect QEMU earlier in boot process

BugLink: https://bugs.launchpad.net/bugs/1838116
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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c
index cad3e8661cd6cf1895c8b69605dbdad730a4c8e6..4d712c1d64b8eee33c8a8b721e7b071d2a92e32a 100644 (file)
--- a/arch/parisc/kernel/process.c
+++ b/arch/parisc/kernel/process.c
@@ -209,12 +209,6 @@ 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 0e9675f857a5ca910769b8de1335cd318d0e2c9d..4736b65c39ecbf0edb393e3aba689ab7463ff694 100644 (file)
--- a/arch/parisc/kernel/setup.c
+++ b/arch/parisc/kernel/setup.c
@@ -406,6 +406,9 @@ 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();