diff options
| author | Sean Anderson <sean.anderson@seco.com> | 2022-05-19 18:26:05 -0400 |
|---|---|---|
| committer | Tom Rini <trini@konsulko.com> | 2022-06-06 18:01:21 -0400 |
| commit | ba9aa40bb387385b8ef8b6594661a97ddcb8d04c (patch) | |
| tree | 9686a914e4337f3d78c8b324729774f74fc9ce05 /boot | |
| parent | f2ebaaa9f38dddddefaf2e616a9fc489fe8b4021 (diff) | |
| download | u-boot-ba9aa40bb387385b8ef8b6594661a97ddcb8d04c.tar.gz | |
bootm: Fix Linux silent console on newer kernels
Linux determines its console based on several sources:
1. the console command line parameter
2. device tree (e.g. /chosen/stdout-path)
3. various other board- and arch-specific sources
If the console parameter specifies a real console (e.g. ttyS0) then that is
used as /dev/console. However, if it does not specify a real console (e.g.
ttyDoesntExist) then *nothing* will be used as /dev/console.
Reading/writing it will return ENODEV. Additionally, no other source will
be used as a console source.
Linux commit ab4af56ae250 ("printk/console: Allow to disable console output
by using console="" or console=null") recently changed the semantics of the
parameter. Previously, specifying console="" would be treated like
specifying some other bad console. This commit changed things so that it
added /dev/ttynull as a console (if available). However, it also allows
for other console sources. If the device tree specifies a console (such as
if U-Boot and Linux share a device tree), then it will be used in addition
to /dev/ttynull. This can result in a non-silent console.
To avoid this, explicitly set ttynull as the console. This will disable
other console sources. If CONFIG_NULL_TTY is disabled, then this will have
the same behavior as in the past (no output, and writing /dev/console
returns ENODEV).
[1] and [2] have additional background on this kernel change.
[1] https://lore.kernel.org/all/20201006025935.GA597@jagdpanzerIV.localdomain/
[2] https://lore.kernel.org/all/20201111135450.11214-1-pmladek@suse.com/
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Diffstat (limited to 'boot')
| -rw-r--r-- | boot/bootm.c | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/boot/bootm.c b/boot/bootm.c index 714406ab668..dfa65f125e5 100644 --- a/boot/bootm.c +++ b/boot/bootm.c @@ -498,7 +498,8 @@ ulong bootm_disable_interrupts(void) } #define CONSOLE_ARG "console=" -#define CONSOLE_ARG_SIZE sizeof(CONSOLE_ARG) +#define NULL_CONSOLE (CONSOLE_ARG "ttynull") +#define CONSOLE_ARG_SIZE sizeof(NULL_CONSOLE) /** * fixup_silent_linux() - Handle silencing the linux boot if required @@ -550,21 +551,22 @@ static int fixup_silent_linux(char *buf, int maxlen) char *end = strchr(start, ' '); int start_bytes; - start_bytes = start - cmdline + CONSOLE_ARG_SIZE - 1; + start_bytes = start - cmdline; strncpy(buf, cmdline, start_bytes); + strncpy(buf + start_bytes, NULL_CONSOLE, CONSOLE_ARG_SIZE); if (end) - strcpy(buf + start_bytes, end); + strcpy(buf + start_bytes + CONSOLE_ARG_SIZE - 1, end); else - buf[start_bytes] = '\0'; + buf[start_bytes + CONSOLE_ARG_SIZE] = '\0'; } else { - sprintf(buf, "%s %s", cmdline, CONSOLE_ARG); + sprintf(buf, "%s %s", cmdline, NULL_CONSOLE); } if (buf + strlen(buf) >= cmdline) return -ENOSPC; } else { - if (maxlen < sizeof(CONSOLE_ARG)) + if (maxlen < CONSOLE_ARG_SIZE) return -ENOSPC; - strcpy(buf, CONSOLE_ARG); + strcpy(buf, NULL_CONSOLE); } debug("after silent fix-up: %s\n", buf); |