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parisc: Detect QEMU earlier in boot process

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commit d006e95b55 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: 310d82784f ("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>
This commit is contained in:
Helge Deller 2019-04-02 12:13:27 +02:00 committed by Greg Kroah-Hartman
parent c1d361d3b1
commit a1f5209663
2 changed files with 3 additions and 6 deletions
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6
arch/parisc/kernel/process.c
View File

@ -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);

3
arch/parisc/kernel/setup.c
View File

@ -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();
set_firmware_width_unlocked();