docs: add SR Band OS diagnostics guide

docs/sr_band_os_test_guide.md

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+# SystemReady Band OS Run Guide
+
+## Overview
+
+This document explains how to run the Linux OS-side diagnostics for SystemReady Band.
+
+The OS run collects debug logs from the installed operating system and runs additional Linux diagnostics. The generated logs are packaged so they can be copied into the ACS results template and validated by the parser.
+
+## Scripts Used
+
+The OS run uses the following scripts:
+
+| File | Purpose |
+|------|---------|
+| [`linux_init.sh`](../common/linux_scripts/linux_init.sh) | Initializes the OS run and triggers ACS or OS log collection flow |
+| [`linux_dump.sh`](../common/linux_scripts/linux_dump.sh) | Collects Linux system dump logs |
+| [`ethtool-test.py`](../common/linux_scripts/ethtool-test.py) | Perfoms Ethernet interface checks |
+| [`read_write_check_blk_devices.py`](../common/linux_scripts/read_write_check_blk_devices.py) | Performs read/write checks on block devices |
+| [`system_config.txt`](../common/config/system_config.txt) | System configuration input used by the scripts |
+
+> **Note**: Please download the latest OS script files from the **[SystemReady-ACS Daily artifacts](https://github.com/ARM-software/arm-systemready/actions/workflows/systemready_daily.yml)**.
+
+### Script Flow
+
+```text
+linux_init.sh
+    ├── detects OS mode
+    ├── installs required tools
+    ├── calls linux_dump.sh
+    ├── runs read_write_check_blk_devices.py to validate block devices using read checks and optional write checks.
+    ├── runs ethtool-test.py to validate Ethernet interfaces using link, ethtool, IP, ping, wget, and curl checks.
+    ├── creates systemready-band-compliance-logs.tar.gz
+    └── prints where to copy the generated OS logs for ACS parser use
+
+linux_dump.sh
+    ├── collects Linux debug dump logs
+    ├── captures firmware, ACPI, UEFI, RTC, PCI, CPU, memory, USB, and block-device information
+    ├── performs system time and hardware clock set checks
+    └── restores OS time synchronization using chronyd or systemd-timesyncd when available
+```
+
+## How to Run
+From the directory containing the scripts, run the script with root privileges.
+```sh
+chmod +x linux_init.sh
+```
+```sh
+sudo ./linux_init.sh --mode os
+```
+
+## Generated Log Directory
+
+The OS logs are generated under the user’s home directory:
+```text
+$HOME/systemready-band-compliance-logs/
+```
+
+At the end of the run, the script creates:
+```text
+systemready-band-compliance-logs.tar.gz
+```
+
+## Logs Collected
+
+The OS run collects the following Linux debug logs:
+```text
+dmesg.txt
+lspci.txt
+lspci-vvv.txt
+cat-proc-interrupts.txt
+cat-proc-cpuinfo.txt
+cat-proc-meminfo.txt
+cat-proc-iomem.txt
+lscpu.txt
+lsblk.txt
+lsusb.txt
+lshw.txt
+dmidecode.txt
+dmidecode.bin
+uname-a.txt
+cat-etc-os-release.txt
+date.txt
+timedatectl.txt
+cat-proc-driver-rtc.txt
+hwclock.txt
+efibootmgr.txt
+efibootmgr-t-20.txt
+efibootmgr-t-5.txt
+efibootmgr-c.txt
+ifconfig.txt
+ip-addr-show.txt
+ping-c-5-www-arm-com.txt
+cat-proc-cmdline.txt
+df-h.txt
+mount.txt
+lsmod.txt
+acpi.log
+*.dat
+*.dsl
+acpixtract.txt
+iasl.txt
+date-set-202212150530.txt
+date-after-set.txt
+hw-clock-set-20230101091015.txt
+hwclock-after-set.txt
+firmware.txt
+firmware/
+time-sync-restore.txt
+```
+
+Additional diagnostic logs:
+
+```text
+read_write_check_blk_devices.log
+ethtool-test.log
+```
+
+
+## Copying OS Logs for ACS Parser
+
+After the OS run completes, copy the generated OS logs into the ACS results template.
+
+Expected destination:
+
+```text
+acs_results_template/os-logs/<linux-os-name>/systemready-band-compliance-logs/
+```
+
+Directory structure:
+
+```text
+acs_results_template/
+└── os-logs/
+    └── linux-<os-name>/
+        └── systemready-band-compliance-logs/
+            ├── dmesg.txt
+            ├── lspci.txt
+            ├── cat-etc-os-release.txt
+            ├── ethtool-test.log
+            ├── read_write_check_blk_devices.log
+            └── other OS logs
+```
+--------------
+*Copyright (c) 2026, Arm Limited and Contributors. All rights reserved.*