From fa9907d20fc650b35ccc1cde9d62d3ef3cf1e145 Mon Sep 17 00:00:00 2001 From: hailin cai Date: Tue, 23 Feb 2016 15:20:31 -0500 Subject: [PATCH] Update Booting/linux-bootstrap-2md.md --- Booting/linux-bootstrap-2md.md | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) mode change 100755 => 100644 Booting/linux-bootstrap-2md.md diff --git a/Booting/linux-bootstrap-2md.md b/Booting/linux-bootstrap-2md.md old mode 100755 new mode 100644 index 658426c..af38404 --- a/Booting/linux-bootstrap-2md.md +++ b/Booting/linux-bootstrap-2md.md @@ -358,19 +358,23 @@ ENDPROC(memset) 到这里位置，全局堆就被正确初始化了。在全局堆被初始化之后，我们就可以使用`GET_HEAP`方法。至于这个函数的实现和使用，我们将在后续的章节中看到。 -CPU validation +检查CPU类型 -------------------------------------------------------------------------------- -The next step as we can see is cpu validation by `validate_cpu` from [arch/x86/boot/cpu.c](https://github.com/torvalds/linux/blob/master/arch/x86/boot/cpu.c). +在堆栈初始化之后，内核代码通过调用[arch/x86/boot/cpu.c](https://github.com/torvalds/linux/blob/master/arch/x86/boot/cpu.c)提供的`validate_cpu`方法检查CPU类型以确定系统是否能够在当前的CPU上运行。 + +`validate_cpu`调用了[`check_cpu`](https://github.com/torvalds/linux/blob/master/arch/x86/boot/cpucheck.c#L102)方法得到当前系统的CPU级别，并且和系统预设的最低CPU级别进行比较。如果不满足条件，则不允许系统运行。function and passes cpu level and required cpu level to it and checks that the kernel launches on the right cpu level. -It calls the [`check_cpu`](https://github.com/torvalds/linux/blob/master/arch/x86/boot/cpucheck.c#L102) function and passes cpu level and required cpu level to it and checks that the kernel launches on the right cpu level. ```c +/*from cpu.c*/ check_cpu(&cpu_level, &req_level, &err_flags); if (cpu_level < req_level) { - ... + printf("This kernel requires an %s CPU, ", cpu_name(req_level)); + printf("but only detected an %s CPU.\n", cpu_name(cpu_level)); return -1; } ``` + `check_cpu` checks the cpu's flags, presence of [long mode](http://en.wikipedia.org/wiki/Long_mode) in case of x86_64(64-bit) CPU, checks the processor's vendor and makes preparation for certain vendors like turning off SSE+SSE2 for AMD if they are missing, etc. Memory detection