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SubjectRe: [PATCH 4.9 64/76] parisc: Detect QEMU earlier in boot process
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Hi Greg,

please do NOT apply this patch to the 4.9 tree.
See below, it was tagged for v4.14+ only.
It breaks the build on 4.9, I got a 0-day build bug about it.

Thanks,
Helge


On 15.04.19 20:44, Greg Kroah-Hartman wrote:
> From: Helge Deller <deller@gmx.de>
>
> 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>
>
> ---
> arch/parisc/kernel/process.c | 6 ------
> arch/parisc/kernel/setup.c | 3 +++
> 2 files changed, 3 insertions(+), 6 deletions(-)
>
> --- 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);
>
> --- 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();
>
>
>

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