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Subject[PATCH v2 3/9] xen/x86: make "earlyprintk=xen" work better for PVH Dom0
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The xen_hvm_early_write() path better wouldn't be taken in this case;
while port 0xE9 can be used, the hypercall path is quite a bit more
efficient. Put that first, as it may also work for DomU-s (see also
xen_raw_console_write()).

While there also bail from the function when the first
domU_write_console() failed - later ones aren't going to succeed.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>

--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -632,17 +632,16 @@ static void xenboot_write_console(struct
unsigned int linelen, off = 0;
const char *pos;

+ if (dom0_write_console(0, string, len) >= 0)
+ return;
+
if (!xen_pv_domain()) {
xen_hvm_early_write(0, string, len);
return;
}

- dom0_write_console(0, string, len);
-
- if (xen_initial_domain())
+ if (domU_write_console(0, "(early) ", 8) < 0)
return;
-
- domU_write_console(0, "(early) ", 8);
while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
linelen = pos-string+off;
if (off + linelen > len)
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