From 55fe269eaa3bd3f63b8672119aa1e96ae30f26db Mon Sep 17 00:00:00 2001 From: Andreas Baumann Date: Thu, 27 Apr 2017 13:46:59 +0200 Subject: moved and added docu on picoc and xv6 --- doc/README.Wyoos | 28 ++++++++++++++++++++++++++++ doc/README.xv6 | 9 +++++++++ 2 files changed, 37 insertions(+) create mode 100644 doc/README.Wyoos create mode 100644 doc/README.xv6 (limited to 'doc') diff --git a/doc/README.Wyoos b/doc/README.Wyoos new file mode 100644 index 0000000..fa96fc8 --- /dev/null +++ b/doc/README.Wyoos @@ -0,0 +1,28 @@ +IDT interupt descriptor table + +GDT global descriptor table +- set up segments +- code segments, RX, never W +- data segments, RW, never X +- 16-bit compatibility on Intel, so quite a nightmare +- asm( LGDT ) needed +=> we do GTD all in assembly, not really readable! Ideal would be to + do as much as possible in C/C++ (even with some zero-overhead + C++17 crazyness maybe) and then call a pure assembly function with + a pointer to the GTD doing the 'LGDT' assembly operation + +types: +- have local typedefs for DWORD32 or uint32_t (as Windows and POSIX did + it) + +keyboard: +- 0x20 PIC +- asm( outb( port, byte)), outb function => better have ports knowing + their own bandwith. + SlowPort8, slowing down assembly code + +interrupts: +- assember stubs translating calling conventions to static C++ function + handling the interrupt number NO + + diff --git a/doc/README.xv6 b/doc/README.xv6 new file mode 100644 index 0000000..c5b9395 --- /dev/null +++ b/doc/README.xv6 @@ -0,0 +1,9 @@ +xv6 is nice, but requires gcc + +picoc: github.com/Prashant47/picoc +guy had the same idea of a self-hosting and self-compiling +cc in xv6. + +No perl, no make, and no funny business in the C compiler. +One issue will be the linker. Either go back to binary or +a.out format or using ELF (juck). -- cgit v1.2.3-54-g00ecf