On 10.01.26 00:18, Stefano Stabellini wrote:
Xen can support console_io hypercalls for any domains, not just dom0,
depending on DEBUG and XSM policies. These hypercalls can be very useful
for development and debugging.

Introduce a kernel command line option xen_console_io to enable the
usage of console_io hypercalls for any domain upon request. When
xen_console_io is not specified, the current behavior is retained.

Signed-off-by: Stefano Stabellini <[email protected]>
---
  .../admin-guide/kernel-parameters.txt         |  5 +++
  drivers/tty/hvc/hvc_xen.c                     | 33 ++++++++++++++++---
  2 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt 
b/Documentation/admin-guide/kernel-parameters.txt
index e88505e945d52..953d3f597f007 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -7620,6 +7620,11 @@
                        save/restore/migration must be enabled to handle larger
                        domains.
+ xen_console_io [XEN,EARLY]
+                       Boolean option to enable/disable the usage of the Xen
+                       console_io hypercalls to read and write to the console.
+                       Mostly useful for debugging and development.
+
        xen_emul_unplug=                [HW,X86,XEN,EARLY]
                        Unplug Xen emulated devices
                        Format: [unplug0,][unplug1]
diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
index 388a71afd6efe..299b08c90bab1 100644
--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -51,6 +51,28 @@ static DEFINE_SPINLOCK(xencons_lock);
/* ------------------------------------------------------------------ */ +static bool xen_console_io = false;
+static int __initdata opt_console_io = -1;
+
+static int __init parse_xen_console_io(char *arg)
+{
+       if (!arg)
+               return -EINVAL;
+
+       if (strcmp(arg, "off") == 0 ||
+           strcmp(arg, "disabled") == 0 ||
+           strcmp(arg, "0") == 0) {
+               opt_console_io = 0;
+       }
+       else if (strcmp(arg, "on") == 0 ||
+                strcmp(arg, "enabled") == 0 ||
+                strcmp(arg, "1") == 0) {
+               opt_console_io = 1;
+       }

I'd prefer use of kstrtobool() instead of open-coding something similar.


Juergen

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