robin.thoni/ipxe - git rthoni.com

Geoff Lywood a4023e02e8 [comboot] Run com32 programs with a valid IDT COM32 binaries generally expect to run with interrupts enabled. Syslinux does so, and COM32 programs will execute cli/sti pairs when running a critical section, to provide mutual exclusion against BIOS interrupt handlers. Previously, under iPXE, the IDT was not valid, so any interrupt (e.g. a timer tick) would generally cause the machine to triple fault. This change introduces code to: - Create a valid IDT at the same location that syslinux uses - Create an "interrupt jump buffer", which contains small pieces of code that simply record the vector number and jump to a common handler - Thunk down to real mode and execute the BIOS's interrupt handler whenever an interrupt is received in a COM32 program - Switch IDTs and enable/disable interrupts when context switching to and from COM32 binaries Testing done: - Booted VMware ESX using a COM32 multiboot loader (mboot.c32) - Built with GDBSERIAL enabled, and tested breakpoints on int22 and com32_irq - Put the following code in a COM32 program: asm volatile ( "sti" ); while ( 1 ); Before this change, the machine would triple fault immediately. After this change, it hangs as expected. Under Bochs, it is possible to see the interrupt handler run, and the current time in the BIOS data area gets incremented. Signed-off-by: Stefan Hajnoczi <stefanha@gmail.com> Signed-off-by: Michael Brown <mcb30@ipxe.org>		vor 15 Jahren
contrib	[errcode] Remove unused contrib/errcode scripts	vor 15 Jahren
src	[comboot] Run com32 programs with a valid IDT	vor 15 Jahren
COPYING	Initial revision	vor 20 Jahren
COPYRIGHTS	[build] Rename gPXE to iPXE	vor 15 Jahren
README	[doc] Re-add README file	vor 15 Jahren

iPXE README File

Quick start guide:

   cd src
   make

For any more detailed instructions, see http://ipxe.org