bios

What does Bios do after Booting

由 旧巷老猫 提交于 2019-12-13 08:10:24
问题 Does BIOS do something after booting? IO in BIOS mean input/output but isn`t bios used only when booting process? If BIOS is not used how can operating system interact with other hardware? 回答1: Read wikipage about BIOS & booting & firmware & UEFI With current operating systems (in particular Linux, for which you'll find a big lot of documentation & resources; notice that Linux & coreboot is free software, so you can study its source code), the BIOS is (nearly) only useful to load the boot

Stopwatch.GetTimeStamp on multiprocessors

由 ☆樱花仙子☆ 提交于 2019-12-13 07:25:49
问题 Stopwatch.GetTimeStamp() may return different timing results on different processors because of bugs in the BIOS or the Hardware Abstraction Layer. Does anyone know what these bugs hold in store in concrete terms? Could timestamps on different processors potentially be totally unrelated - or would they be only off by some small amount (sub-milliseconds?) at most? Could numbers on different processors drift apart over time - which then would in effect lead to the aforementioned "timestamps

Access BIOS/UEFI menu setting via uefi shell

由 元气小坏坏 提交于 2019-12-13 04:14:15
问题 I´d like to read/alter some BIOS/UEFI menu settings via a uefi shell script. For example I´d like to change the 'CSM Support' setting (Enabled/Disabled). Is there any way to do so? 回答1: Inspect the uefi variables (not shell variables) before and after you change the 'CSM Support' setting, maybe this setting is stored in one of the uefi variables, you can then edit this variable from the shell or a simple shell app. 来源： https://stackoverflow.com/questions/52756635/access-bios-uefi-menu-setting

How to use real mode BIOS / VESA calls from GRUB?

由 我只是一个虾纸丫 提交于 2019-12-12 06:04:21
问题 I am developing a simple Grub module which would enable some additional video settings/initializations at the early stage of the boot process. My actual best idea would be to use some VESA calls for the task. Unfortunately, recently I've found real mode calls are unavailable from the Grub. But the GRUB can do really complex operations which are probably unimaginable without the help of the BIOS. How is it possible? How could I call the bios from the grub? 回答1: As far as I can see, grub uses

Why doesn't BIOS load the Linux Kernel directly - why the MBR and all that trouble?

由 白昼怎懂夜的黑 提交于 2019-12-12 01:29:46
问题 I've recently learned about the boot process for Linux. I can't help but wonder why we go through the trouble of acccessing the MBR after BIOS so that instructions there can, in turn, load the kernel into RAM. Why the middle man - why doesn't BIOS load the kernel directly? 回答1: Because otherwise any time you used a different disk or file system you would need to rewrite the instructions in the BIOS. The MBR is an intermediary that handles that on behalf of the BIOS, knowing where to go to for

reading the system clock value?

由 偶尔善良 提交于 2019-12-11 20:43:48
问题 Is there a virtual/system clock running independently when a computer is booted? How can we read that value? 回答1: Use the RDTSC x86 instruction, it reads the clocks since the system-start. Edit: On x86-64 targets the use of inline assembly is not possible anymore, use either intrinics or a external linked object file which was generated by an assembler. Do not forget to flush the processor pipeline before using this instruction. 来源： https://stackoverflow.com/questions/3253387/reading-the

About USB boot from usb

由 生来就可爱ヽ(ⅴ＜●) 提交于 2019-12-11 17:45:52
问题 I want to make ipl and boot os from my usb. I just want to read 360 sectors(512 bytes per sector).I checked code for several times and cannot find some mistakes.I have already debug it on qemu but it always returns "load error"(as in this code, it jumps to error section).It seems lba search did not work and always get carry flag 1 when I do it. my qemu program is like this qemu-system-i386 -usb ipl.bin and ipl.bin is compiled binary file made from assembler code below. ; haribote-ipl ; TAB=4

PC与Android分别是如何启动的？

由 旧巷老猫 提交于 2019-12-11 12:06:59
大佬详细讲解 个人纪录: pc： 程序与系统都是存放在硬盘中，启动时需要从硬盘读取到内存中，再加载到cpu中运行 按下开机键会先启动bios（基本输入输出系统），bios读取到硬盘中的系统，把系统加载到cpu中的开始运行系统 bios启动时会先自我检测如果有问题就会发出响声来提示（不同的错误响声次数不同和长度）， 如果没问题则会按照bios中的Boot Sequence（启动顺序）来启动相应的系统（重装系统时需要设置u盘的启动顺数为第一位就是利用了这个） android： 没有bios，有的是bootloader（与bios的作用一样） ROM（只读存储器）相当于pc的硬盘。（RAM（读写存储器）） 那么 Bootloader 是如何被加载的呢？跟 PC 启动过程类似，当开机通电时首先会加载 Bootloader，Bootloader 会读取 ROM 找到操作系统并将 Linux 内核加载到 RAM 中。 Linux 内核加载的最后阶段会启动执行第一个用户空间进程 init 进程 来源： CSDN 作者： 小矮子tt 链接： https://blog.csdn.net/qq_38287890/article/details/103489472

How to tell under Linux which disk will be used by BIOS to boot?

由 ╄→гoц情女王★ 提交于 2019-12-11 07:48:57
问题 How to print from CMOS which device will be used as boot device after reboot? Computer has several sata disk drives and several bootable USB-devices attached. The layout of CMOS memory is defined by version of BIOS used. I know that there are several different versions and manufacturers of BIOSes. I think it is possible to determine which one is used by examining BIOS memory. Somehow like in this question - How to check the BIOS version or name in Linux through a command prompt? My computer

How can early BIOS use CALL?

由 我只是一个虾纸丫 提交于 2019-12-11 07:38:33
问题 I am, purely for hobby reasons, trying to understand some low-level code in the PC. I downloaded an outdated BIOS ROM image for a random old Gigabyte MB (https://www.gigabyte.com/Motherboard/GA-8I845GE775-G-rev-10/support#support-dl-bios), it's almost 15 years old so I hope it doesn't harm anyone's IP rights. I'll be using this file for reference. I'm stumbled right at the beginning. These seem to be the very first instructions the processor sees after power up: f000:fff0 ljmp 0xf000:0xe05b
订阅 bios