I've spent about an hour searching without finding an answer. Is there any way from the kernel command line (i.e. by editing the GRUB entry) to control the number of lines on the console? I installed Fedora 39 on a USB stick so that I can use it to boot other computers to diagnose problems with the installed OS. The problem is that when it is booting, the latest console messages are off the bottom of the screen so that I can't see what it's doing (this is on a standard 1920x1080 HD monitor in this case). If the boot hangs, then of course the last few messages are the crucial ones to see.
Once the machine is booted, of course, then I can log in and use tools such as "stty" to set the number of rows and cure this problem, but I need something that will take effect during system startup before the login prompt comes up.
Thank you, --Greg
Hi,
The problem is that when it is booting, the latest console messages are off the bottom of the screen so that I can't see what it's doing
How does that look exactly? I mean how are you sure there are some more lines you can't see ? Do you see the last line like a cut in half suggesting there's more off-screen ?
If the Full HD resolution isn't working well in your setup, you may try to force a lower resolution by trying out 'video=1024x768' or 'vga=0x318' kernel parameters.
--
Michal Schorm Software Engineer Core Services - Databases Team Red Hat
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On Thu, Jun 6, 2024 at 6:01 PM Greg Woods greg@gregandeva.net wrote:
I've spent about an hour searching without finding an answer. Is there any way from the kernel command line (i.e. by editing the GRUB entry) to control the number of lines on the console? I installed Fedora 39 on a USB stick so that I can use it to boot other computers to diagnose problems with the installed OS. The problem is that when it is booting, the latest console messages are off the bottom of the screen so that I can't see what it's doing (this is on a standard 1920x1080 HD monitor in this case). If the boot hangs, then of course the last few messages are the crucial ones to see.
Once the machine is booted, of course, then I can log in and use tools such as "stty" to set the number of rows and cure this problem, but I need something that will take effect during system startup before the login prompt comes up.
Thank you, --Greg
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On Thu, Jun 6, 2024 at 10:12 AM Michal Schorm mschorm@redhat.com wrote:
The problem is that when it is booting, the latest console messages are
off the bottom of the screen so that I can't see what it's doing
How does that look exactly? I mean how are you sure there are some more lines you can't see ? Do you see the last line like a cut in half suggesting there's more off-screen ?
Yes, for one thing. Also there are times when it has stopped outputting messages, then later starts again and a message goes by that tells me what was hanging it up (certain things, like updating kernel packages, are slow, so when that message goes by, I can guess that this is what it was doing when the output temporarily stopped).
If the Full HD resolution isn't working well in your setup, you may
try to force a lower resolution by trying out 'video=1024x768' or 'vga=0x318' kernel parameters.
I have tried a couple of different vga values but it has no apparent effect; I probably just haven't hit on the right one yet. I was kind of hoping someone here would have already seen this problem and have some specific values to try. Once the current system-upgrade that is in progress finishes, I'll try the ones you list here.
--Greg
Greg Woods composed on 2024-06-06 11:26 (UTC-0600):
Michal Schorm wrote:
If the Full HD resolution isn't working well in your setup, you may
try to force a lower resolution by trying out 'video=1024x768' or 'vga=0x318' kernel parameters.
I have tried a couple of different vga values but it has no apparent effect; I probably just haven't hit on the right one yet. I was kind of hoping someone here would have already seen this problem and have some specific values to try. Once the current system-upgrade that is in progress finishes, I'll try the ones you list here.
Any valid vga= applied lasts only until a module providing working KMS loads. Once KMS engages, the kernel decides the mode, unless a differing supported video= mode has been applied. If KMS engages early enough, the effect of vga= may never be seen.
Using video= with a suitable value does normally change the mode if KMS is working, and with an appropriate mode, output fitting the available screen space should result. On a 1920x1080, try actually specifying 1920x1080. If that doesn't help, others to try include: 1600x900, 1280x768, 1152x854 & 1024x768. @60 or an alternate refresh rate may be appended to the video= mode, and may make a difference.
On 6/6/24 09:00, Greg Woods wrote:
on a standard 1920x1080 HD monitor in this case). If the boot hangs, then of course the last few messages are the crucial ones to see.
Once the machine is booted, of course, then I can log in and use tools such as "stty" to set the number of rows and cure this problem, but I need something that will take effect during system startup before the login prompt comes up.
These values will be used during boot but they don't kick in until about half way through. You include it by adding it to /etc/default/grub and running grub-mkconfig -o /wherever/your/grub.cfg/is.
GRUB_GFXMODE=1920x1080
On 6/6/24 9:00 AM, Greg Woods wrote:
I've spent about an hour searching without finding an answer. Is there any way from the kernel command line (i.e. by editing the GRUB entry) to control the number of lines on the console? I installed Fedora 39 on a USB stick so that I can use it to boot other computers to diagnose problems with the installed OS. The problem is that when it is booting, the latest console messages are off the bottom of the screen so that I can't see what it's doing (this is on a standard 1920x1080 HD monitor in this case). If the boot hangs, then of course the last few messages are the crucial ones to see.
That shouldn't be possible. The number of lines is directly related to the screen resolution. The only way I can see this happening is if it thinks there's another monitor attached with a higher resolution. Do you see any information about the display resolution in the logs?
On Thu, Jun 6, 2024 at 2:11 PM Samuel Sieb samuel@sieb.net wrote:
The problem is that when it is booting,
the latest console messages are off the bottom of the screen so that I
can't see what it's doing (this is on a standard 1920x1080 HD monitor in this case). If the boot hangs, then of course the last few messages are the crucial ones to see.
That shouldn't be possible. The number of lines is directly related to the screen resolution. The only way I can see this happening is if it thinks there's another monitor attached with a higher resolution. Do you see any information about the display resolution in the logs?
This is likely the problem. The machine I'm working on is a laptop that has a 4K screen. The lid is closed so the 4K screen is not actually being used, and the laptop is connected to the monitor through a dock, and this is where I see the boot messages. I do this when doing console work because when the system boots on the 4K screen, the type face is too small for this old geezer to read.
So I have verified that if I boot the Fedora USB stick on my desktop using the same monitor, the problem does not occur, and if I boot the stick on the laptop without the dock and with the lid open, aside from the fact that the text is too small to read on the 4K screen, the problem does not occur. When I boot this laptop from its own native OS rather than from the stick, I have kernel command line parameters (vconsole.font=latarcyrheb-sun32.psfu.gz SYSFONT=latarcyrheb-sun32.psfu.gz) that make the booting text larger so I can read it, and the problem also does not occur. It also makes the font larger that appears on the text consoles. This is not so great for booting from the stick though; I have a hard time entering these parameters correctly when editing a GRUB entry when I cannot check what I am typing. I also tried playing games with video= values, and it works while boot messages are printing, but once the login prompt comes up, the font is tiny again. I suppose there must be a solution to this somewhere but I have already spent enough time on it. I was just hoping to learn a little something about the boot process.
--Greg
On 6/6/24 5:00 PM, Greg Woods wrote:
rather than from the stick, I have kernel command line parameters (vconsole.font=latarcyrheb-sun32.psfu.gz SYSFONT=latarcyrheb-sun32.psfu.gz) that make the booting text larger so I can read it, and the problem also does not occur. It also makes the font larger that appears on the text consoles. This is not so great for booting from the stick though; I have a hard time entering these parameters correctly when editing a GRUB entry when I cannot check what I am typing. I also tried playing games with video= values, and it works while boot messages are printing, but once the login prompt comes up, the font is tiny again. I suppose there must be a solution to this somewhere but I have already spent enough time on it. I was just hoping to learn a little something about the boot process.
You could edit the grub entry on the USB stick from another computer to add those options.
On Thu, Jun 6, 2024 at 7:06 PM Samuel Sieb samuel@sieb.net wrote:
On 6/6/24 5:00 PM, Greg Woods wrote:
I hve kernel command line parameters
(vconsole.font=latarcyrheb-sun32.psfu.gz
SYSFONT=latarcyrheb-sun32.psfu.gz) that make the booting text larger so I can read it, and the problem also does not occur
You could edit the grub entry on the USB stick from another computer to add those options.
Yes I could. But the point of having the stick is to be able to boot from it on any PC. I don't want to enter something that is specific to this laptop on the stick.
--Greg
On 6/6/24 6:29 PM, Greg Woods wrote:
On Thu, Jun 6, 2024 at 7:06 PM Samuel Sieb <samuel@sieb.net mailto:samuel@sieb.net> wrote: You could edit the grub entry on the USB stick from another computer to add those options.
Yes I could. But the point of having the stick is to be able to boot from it on any PC. I don't want to enter something that is specific to this laptop on the stick.
You could add an extra entry to the boot menu.
On Thu, Jun 6, 2024 at 8:24 PM Samuel Sieb samuel@sieb.net wrote:
You could add an extra entry to the boot menu.
That's a thought. Of course one of the reasons I wanted to learn more about the boot process is that it has changed so much since I was working as a sysadmin, now that I'm retired I haven't kept up with everything as well as I used to. So I have to admit that now, I don't even know how to do that. Something else I need to learn.
--Greg
Greg Woods composed on 2024-06-06T20:55 (UTC-0600):
Samuel Sieb wrote:
You could add an extra entry to the boot menu.
That's a thought. Of course one of the reasons I wanted to learn more about the boot process is that it has changed so much since I was working as a sysadmin, now that I'm retired I haven't kept up with everything as well as I used to. So I have to admit that now, I don't even know how to do that. Something else I need to learn.
https://forums.opensuse.org/t/how-to-have-a-custom-uefi-grub-menu-for-a-multiboot-system/133541 could help you get that started. /etc/grub.d/40_custom and 41_custom are designed for custom stanza creations. If you wish their result to head the selections in you Grub menu, you must rename whichever you choose to use so that it sorts before 10_linux. I use both avenues, so copy 40_custom to 06_custom, and 41_custom to 07_custom. Updates will at some point restore the original 40_custom and 41_custom, unless you keep and either empty them or make them nothing but comments.
On 6/6/24 8:45 PM, Felix Miata wrote:
Greg Woods composed on 2024-06-06T20:55 (UTC-0600):
Samuel Sieb wrote:
You could add an extra entry to the boot menu.
That's a thought. Of course one of the reasons I wanted to learn more about the boot process is that it has changed so much since I was working as a sysadmin, now that I'm retired I haven't kept up with everything as well as I used to. So I have to admit that now, I don't even know how to do that. Something else I need to learn.
https://forums.opensuse.org/t/how-to-have-a-custom-uefi-grub-menu-for-a-multiboot-system/133541 could help you get that started. /etc/grub.d/40_custom and 41_custom are designed for custom stanza creations. If you wish their result to head the selections in you Grub menu, you must rename whichever you choose to use so that it sorts before 10_linux. I use both avenues, so copy 40_custom to 06_custom, and 41_custom to 07_custom. Updates will at some point restore the original 40_custom and 41_custom, unless you keep and either empty them or make them nothing but comments.
This was just for a live image. There's no need to get that crazy complicated. That's only for a multi-boot system. Adding items to a single boot system is very simple.
Samuel Sieb composed on 2024-06-06 20:53 (UTC-0700):
Felix Miata wrote:
https://forums.opensuse.org/t/how-to-have-a-custom-uefi-grub-menu-for-a-multiboot-system/133541 could help you get that started. /etc/grub.d/40_custom and 41_custom are designed for custom stanza creations. If you wish their result to head the selections in you Grub menu, you must rename whichever you choose to use so that it sorts before 10_linux. I use both avenues, so copy 40_custom to 06_custom, and 41_custom to 07_custom. Updates will at some point restore the original 40_custom and 41_custom, unless you keep and either empty them or make them nothing but comments.
This was just for a live image. There's no need to get that crazy complicated. That's only for a multi-boot system. Adding items to a single boot system is very simple.
Adding a stanza to 40_custom is not complicated. That URL is mainly example of configuring grub, getting to know how it does what it does, good for people who learn better from reading and/or working with examples than reading man pages.
On 6/6/24 9:02 PM, Felix Miata wrote:
Samuel Sieb composed on 2024-06-06 20:53 (UTC-0700):
Felix Miata wrote:
https://forums.opensuse.org/t/how-to-have-a-custom-uefi-grub-menu-for-a-multiboot-system/133541 could help you get that started. /etc/grub.d/40_custom and 41_custom are designed for custom stanza creations. If you wish their result to head the selections in you Grub menu, you must rename whichever you choose to use so that it sorts before 10_linux. I use both avenues, so copy 40_custom to 06_custom, and 41_custom to 07_custom. Updates will at some point restore the original 40_custom and 41_custom, unless you keep and either empty them or make them nothing but comments.
This was just for a live image. There's no need to get that crazy complicated. That's only for a multi-boot system. Adding items to a single boot system is very simple.
Adding a stanza to 40_custom is not complicated. That URL is mainly example of configuring grub, getting to know how it does what it does, good for people who learn better from reading and/or working with examples than reading man pages.
Fedora uses BLS now, so that information is somewhat outdated. It probably still sort of works, but not the best way.
Greg Woods composed on 2024-06-06 18:00 (UTC-0600):
So I have verified that if I boot the Fedora USB stick on my desktop using the same monitor, the problem does not occur, and if I boot the stick on the laptop without the dock and with the lid open, aside from the fact that the text is too small to read on the 4K screen, the problem does not occur. When I boot this laptop from its own native OS rather than from the stick, I have kernel command line parameters (vconsole.font=latarcyrheb-sun32.psfu.gz SYSFONT=latarcyrheb-sun32.psfu.gz) that make the booting text larger so I can read it, and the problem also
If you have this size 32 vconsole.conf configuration on your USB stick, I suggest changing it to something smaller, maybe 24, halfway between 16 & 32.
does not occur. It also makes the font larger that appears on the text consoles. This is not so great for booting from the stick though; I have a hard time entering these parameters correctly when editing a GRUB entry when I cannot check what I am typing. I also tried playing games with video= values, and it works while boot messages are printing, but once the login prompt comes up, the font is tiny again.
Reverting to mousetype is a forseeable result if vga= is used, suitable video= is not used, and KMS is not engaging before gettys startup. Configuring early KMS in initramfs should help if this is the situation.
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Felix Miata -
Greg Woods -
Michal Schorm -
Mike Wright -
Samuel Sieb