[ipxe-devel] serial arrow keys broken

Thu Apr 17 14:24:39 UTC 2014

HI Alex,

That means its sending an escape sequences but the <esc>] bit is being lost.

I believe this is due to only having a single character available to read
from the serial UART (the last one received) after the system generates an
interrupt to bring it out of it out of the cpu_nap sleep routine

That thing I tried was

ipxe/src/core/serial.c

        /* enable and reset fifos, set threshold to max for escape
sequences */
        uart_writeb(0xc3, UART_BASE + UART_FCR)

This seems to work for me, holding down the arrow key can occasionally
result in an esc being read on its own which causes a menu exit.

Enabling read interrupts has no effect but it doesn't break ipxe either.

If I get past that then holding down an arrow key in grub causes and exit
from the menu I was editing (this is a grub problem not ipxe but is
suggests that even this code isn't perfect - maybe rts/cts needs to
beenabled but then that prevents boot if there's no serial connected)

Commenting out the cpu_nap i core/getkey.c should also work but that will
cause the cpu to constantly poll for characters and use more power.

Michael Brown mcb30 at ipxe.org, had a concern over resetting the receive and
transmit fifos by using 0x03 instead of 0x01 but the code immediately
following it drains and pending characters anyway. 0xC0 octet sets the
thresholds as high as possible but this is probably more about delaying
interrupts than making the fifo buffer any quicker and as interrupts are
disabled this probably has no effect.

values to tried all seem to work
0x01 enable fifos only (this is probably enough)
0x03 reset and enable fifos
0xc3 set fifo thresholds reset fifos and enable fifos.

My system is using a motherboard serial device accessed from a direct
serial cable, you are using an Dell iDRAC via java or activex which has
more things to go wrong I guess.

Jarrod Johnson jarrod.b.johnson at gmail.com, pointed out that some vt100 mode
keys send <esc> O A instead of <esc> ] A this that is what is happening the
ipxe will not recognise it but I thing you would get at least OA printed if
the input routine sees all three chars of the escape sequence. I think the
first problem is that its not seeing all the characters.

Michaels patch didn't work for me and I didnt try adjusting
#define GETKEY_TIMEOUT ( TICKS_PER_SEC / 4 )
The suggestion was to change this to 2 which would make it 1/2
sec until read timout instead of 1/4 sec I don't think that will work as
the problem is that 3 chars are received while waiting for
an interrupt and only the last character received is seen as there is no
buffer in the hardware, interrupts are not enabled and there is no isr even
if they were (but it would trigger and immediate exit from cpu_sleep when a
character is received but that still does not seem to be enough .

Porting the interrupt driven serial code from linux is a lot of work and
not worth the effort for input, as Michael pointed out keyboard input is
not performance sensitive,
 but perhaps output would be significantly faster -- still not many ppl
spend all day in ipxe menus.

Thanks

Peter

On 17 April 2014 05:10, Alex Davies <alex at davz.net> wrote:

> A, B, C and D. Here I pressed the key after each word (e.g. “u”, “p”, <up
> arrow”):
>
>
>
> iPXE> up A down B right C left D
>
> up: command not found
>
>
> The graphical console looked like the screenshot below when I entered the
> keys via SOL:
>
>
>
>
>
>
> On Wed, Apr 9, 2014 at 11:48 AM, Peter Pickford <peter at netremedies.ca>wrote:
>
>> If you exit the menu and got to the ipxe command line what do you get
>> when you press the arrow keys?
>>
>>
>> On 9 April 2014 03:41, Alex Davies <alex at davz.net> wrote:
>>
>>> Hi All,
>>>
>>> We had the same problem using SOL on Dell hardware.
>>>
>>> I tried both your patch Michael and the divide by two suggested at the
>>> top of this thread, without joy.
>>>
>>> Interestingly, pressing the arrow key does stop the countdown timer, but
>>> the menu selector does not move, so iPXE is getting something. What debug
>>> flag should I enable to see what it is getting?
>>>
>>> The menu is working nicely with color and if I connect to the 'full
>>> console' via the DRAC, and move the arrow key, the SOL menu refreshes
>>> correctly.
>>>
>>> Thanks!
>>>
>>> -Alex
>>>
>>>
>>> On Thu, Mar 27, 2014 at 2:46 PM, Michael Brown <mcb30 at ipxe.org> wrote:
>>>
>>>> On 27/03/14 08:36, Peter Pickford wrote:
>>>>
>>>>> The arrow keys would not work in my ipxe serial console.
>>>>>
>>>>> The following seems to fix it but causes a busy wait while reading
>>>>> escape sequences.
>>>>>
>>>>> <snip>
>>>>>
>>>>
>>>> Arrow keys over serial works for me.  Could you try the attached
>>>> (untested) patch, which preserves the cpu_nap() while changing the ordering
>>>> of events such that a keypress arriving during the cpu_nap() will be
>>>> detected even if the timeout has expired?
>>>>
>>>> Thanks,
>>>>
>>>> Michael
>>>>
>>>> _______________________________________________
>>>> ipxe-devel mailing list
>>>> ipxe-devel at lists.ipxe.org
>>>> https://lists.ipxe.org/mailman/listinfo.cgi/ipxe-devel
>>>>
>>>>
>>>
>>>
>>> --
>>> Alex Davies
>>>
>>> This email and any files transmitted with it are confidential and
>>> intended solely for the use of the individual or entity to whom they
>>> are addressed. If you have received this email in error please notify
>>> the sender immediately by e-mail and delete this e-mail permanently.
>>>
>>
>>
>
>
> --
> Alex Davies
>
> This email and any files transmitted with it are confidential and
> intended solely for the use of the individual or entity to whom they
> are addressed. If you have received this email in error please notify
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