Re: [PATCH v4 1/1] printk: fix zero-valued printk timestamps in early boot

--000000000000f4474f064f8f93ba
Content-Type: text/plain; charset="UTF-8"

Hi,

In attachment the V6 of the patch, and these are the changes since Tim
proposed it:

V5 -> V6
  Feature moved in the proper menu place, immediately after:
  Kernel hacking -> printk and dmesg options -> show timitng information printks
  Comments and descriptions more clearly indicate the aim and the limits of this
  patch and the related feature introduced by this patch.
V4 -> V5
  Rationale: single point of change hack for printk. Code rewritten, entirely.
  It provides a feature for kernel hackers willing to profiling the early boot
  with a basic printk approach (rather than using HW monitors which might not
  be available or immediately available). Thus, it is a first-look or a last
  resort hack profiling feature. Something that isn't good to spread around
  the kernel sources tree and it is fine to have into a single header file.

    cnfg/printk-early-boot-timestamps-hack-v6.patch: polishing, V6

    Pre-Kernel boot time (qemu, KVM, bios) is 0.251063 / 1.896 = 0.132 seconds

    [    0.250814] Linux version 5.15.202 (roberto@x280) (x86_64-linux-musl-gcc
                   (GCC) 14.3.0, GNU ld (GNU Binutils) 2.44) #1 Thu A6
    [    0.250820] Command line: HOST=x86_64 root=/dev/ram0 init=/init
                   console=ttyS0,115200n8 net.ifnames=0 nokaslr
    [    0.250823] KERNEL supported cpus:
    [    0.250824]   Intel GenuineIntel
    [    0.250826]   AMD AuthenticAMD
    [    0.250972] BIOS-provided physical RAM map:
    [    0.250973] BIOS-e820: [mem 0x0000000000000000-0x000000000009fbff] usable
    [    0.250978] BIOS-e820: [mem
0x000000000009fc00-0x000000000009ffff] reserved
    [    0.250981] BIOS-e820: [mem
0x00000000000f0000-0x00000000000fffff] reserved
    [    0.250983] BIOS-e820: [mem 0x0000000000100000-0x0000000001fdefff] usable
    [    0.250986] BIOS-e820: [mem
0x0000000001fdf000-0x0000000001ffffff] reserved
    [    0.250989] BIOS-e820: [mem
0x00000000b0000000-0x00000000bfffffff] reserved
    [    0.250991] BIOS-e820: [mem
0x00000000fed1c000-0x00000000fed1ffff] reserved
    [    0.250994] BIOS-e820: [mem
0x00000000feffc000-0x00000000feffffff] reserved
    [    0.250996] BIOS-e820: [mem
0x00000000fffc0000-0x00000000ffffffff] reserved
    [    0.251043] NX (Execute Disable) protection: active
    [    0.251050] Hypervisor detected: KVM
    [    0.251053] kvm-clock: Using msrs 4b564d01 and 4b564d00
    [    0.251063] kvm-clock: cpu 0, msr bac001, primary cpu clock
    [    0.000001] kvm-clock: using sched offset of 56130848 cycles
    [    0.000003] clocksource: kvm-clock: mask: 0xffffffffffffffff
                   max_cycles: 0x1cd42e4dffb, max_idle_ns: 881590591483 ns
    [    0.000005] tsc: Detected 1896.002 MHz processor

Best regards, R-

--000000000000f4474f064f8f93ba
Content-Type: text/x-patch; charset="US-ASCII"; 
	name="printk-early-boot-timestamps-hack-v6.patch"
Content-Disposition: attachment; 
	filename="printk-early-boot-timestamps-hack-v6.patch"
Content-Transfer-Encoding: base64
Content-ID: <f_mo17pj6k0>
X-Attachment-Id: f_mo17pj6k0
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--000000000000f4474f064f8f93ba--