Hi Simon, On Wed, Jul 1, 2015 at 10:58 PM, Simon Glass <[email protected]> wrote: > Hi, > > On 1 July 2015 at 02:27, Bin Meng <[email protected]> wrote: >> From: Jian Luo <[email protected]> >> >> PCI option rom may use different SS during its execution, so it is not >> safe to assume esp pointed to the same location in the protected mode. >> >> Signed-off-by: Jian Luo <[email protected]> >> Reviewed-by: Bin Meng <[email protected]> >> Tested-by: Bin Meng <[email protected]> >> --- >> >> arch/x86/lib/bios_asm.S | 15 +++++++++++++++ >> 1 file changed, 15 insertions(+) >> >> diff --git a/arch/x86/lib/bios_asm.S b/arch/x86/lib/bios_asm.S >> index 4faa70e..a29fe0e 100644 >> --- a/arch/x86/lib/bios_asm.S >> +++ b/arch/x86/lib/bios_asm.S >> @@ -246,6 +246,8 @@ __interrupt_handler_16bit = PTR_TO_REAL_MODE(.) >> push %fs >> push %gs >> >> + movw %ss, %cs:__realmode_ss >> + >> /* Clear DF to not break ABI assumptions */ >> cld >> >> @@ -258,12 +260,22 @@ __interrupt_handler_16bit = PTR_TO_REAL_MODE(.) >> >> enter_protected_mode >> > > Please can you add a comment here for the next person who changes > this, about what is going on? It looks like it is saving and restoring > the real mode SS register? >
Will add a comment in v2. >> + movzwl %cs:__realmode_ss, %ecx >> + shll $4, %ecx >> + addl %ecx, %esp >> + >> /* Call the C interrupt handler */ >> movl $interrupt_handler, %eax >> call *%eax >> >> + movzwl %cs:__realmode_ss, %ecx >> + shll $4, %ecx >> + subl %ecx, %esp >> + >> enter_real_mode >> >> + movw %cs:__realmode_ss, %ss >> + >> /* >> * Restore all registers, including those manipulated by the C >> * handler >> @@ -276,6 +288,9 @@ __interrupt_handler_16bit = PTR_TO_REAL_MODE(.) >> popal >> iret >> >> +__realmode_ss = PTR_TO_REAL_MODE(.) >> + .word 0 >> + >> .globl asm_realmode_code_size >> asm_realmode_code_size: >> .long . - asm_realmode_code >> -- Regards, Bin _______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
