Linux学习篇（十）：树莓派优麒麟20.4调整HDMI分辨率

一：树莓派官网对于HDMI 启动配置的介绍：

Video options in config.txt

二：stackexchange网站相关讨论：

Can't find /etc/default/grub

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/etc/default/grub does just not seem to exist on my system. I have a raspberry pi 3b+ running ubuiqityrobot which is an Ubuntu version with ros preinstalled.

I want to find this grub file to edit one line of code to stop the loading dots from boot to remain in the center of my screen. My question is. Where is my /etc/default/grub file?

-----------------------------------------------主要回答：----------------------------------------------------------------------------

Your observation is correct. Raspberry Pi does not use GRUB at all.

GRUB is not universal in the Linux world, but a bootloader for some specific hardware architectures:

• 32- and 64-bit x86 PCs, using BIOS, UEFI or Coreboot firmware
• PowerPCs
• SPARC systems
• MIPS Lemote Yeeloong systems
• certain Qemu emulation environments.

Raspberry Pi is an ARM device, which is none of the above. It has its own firmware and bootloader.

The first stage bootloader is stored in ROM within the RasPi's system-on-chip. It loads bootcode.bin from the SD card. That will load start.elf, which will then load config.txt, cmdline.txt and kernel.img. In older versions of RasPi firmware, there used to be loader.bin step in between bootcode.bin and start.elf.

More details:

https://raspberrypi.stackexchange.com/q/10489

https://www.raspberrypi.org/forums/viewtopic.php?t=6685

config.txt settings: http://rpf.io/configtxtreadme

cmdline.txt is the place for the Linux kernel boot options.  

answered Oct 17 '18 at 8:40    telcoM

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So where can we set the boot resolution on RPI (I know each ARM system has different settings)? Modern Linux on i386 architecture uses KMS and we set GRUB_GFXMODE=1280x800 and GRUB_GFXPAYLOAD_LINUX=keep in /etc/defaults/grub and then rebuilt the Grub with sudo update-grub and sudo reboot. – 71GA Mar 20 at 16:24     -------------------------提问-------------------------------------

• @71GA In /boot/config.txt, there should be commented-out lines with hdmi_group, hdmi_mode, framebuffer_width and framebuffer_height, ready to be uncommented and adjusted as needed. See rpf.io/configtxtreadme for more info. Once the Linux kernel is up and running, there is also the fbset command which can be used to change the display mode as needed. – telcoM Mar 21 at 7:57 　　------------------回复------------------------