Classes
struct	mtrr_range
	mtrr_reconfigure keeps a list of MEM_WB ranges. This structure describes one item in the list. More...

Functions
void	init_pat_mtrr ()
	Initializes PAT (Page Attribute Table) and MTRRs. More...

void	mtrr_begin_change ()

void	mtrr_end_change ()

void	mtrr_reconfigure ()
	Helper procedure for MTRR initialization. Takes MTRR configured by BIOS and tries to recongifure them in order to allow non-UC data at top of 4G memory. Example: if low part of physical memory is 3.5G = 0xE0000000 bytes wide, BIOS can configure two MTRRs so that the first MTRR describes [0, 4G) as WB and the second MTRR describes [3.5G, 4G) as UC; WB+UC=UC, so the resulting memory map would be as needed, but in this configuration our attempts to map LFB at (say) 0xE8000000 as WC would be ignored, WB+UC+WC is still UC. So we must keep top of 4G memory not covered by MTRRs, using three WB MTRRs [0,2G) + [2G,3G) + [3G,3.5G), this gives the same memory map, but allows to add further entries. See mtrrtest.asm for detailed input/output from real hardware+BIOS. More...

void	set_mtrr (dword base, dword size, dword mem_type)
	Allocate&set one MTRR for given range. size must be power of 2 that divides base. More...

void	mtrr_get_real_type ()
	Helper procedure for mtrr_validate. Calculates memory type for given address according to variable-range MTRRs. Assumes that MTRRs are enabled. in: ebx = 32-bit physical address out: eax = memory type for ebx. More...

void	mtrr_validate ()
	If MTRRs are configured improperly, this is not obvious to the user; everything works, but the performance can be horrible. Try to detect this and let the user know that the low performance is caused by some problem and is not a global property of the system. Let's hope he would report it to developers... More...

Variables
dd	num_variable_mtrrs
	number of variable-range MTRRs More...

dd	_phys_reserved_mask

dd	_first_range

dd	_first_free_range

dd	_num_used_mtrrs

dd	_mtrrs_end

rq	_mtrrs

Function Documentation

◆ init_pat_mtrr()

void init_pat_mtrr ( )

Initializes PAT (Page Attribute Table) and MTRRs.

Source: core/mtrr.inc:10

◆ mtrr_begin_change()

void mtrr_begin_change ( )

Source: core/mtrr.inc:42

◆ mtrr_end_change()

void mtrr_end_change ( )

Source: core/mtrr.inc:74

◆ mtrr_get_real_type()

void mtrr_get_real_type ( )

Helper procedure for mtrr_validate. Calculates memory type for given address according to variable-range MTRRs. Assumes that MTRRs are enabled. in: ebx = 32-bit physical address out: eax = memory type for ebx.

Source: core/mtrr.inc:814

◆ mtrr_reconfigure()

void mtrr_reconfigure ( )

Helper procedure for MTRR initialization. Takes MTRR configured by BIOS and tries to recongifure them in order to allow non-UC data at top of 4G memory. Example: if low part of physical memory is 3.5G = 0xE0000000 bytes wide, BIOS can configure two MTRRs so that the first MTRR describes [0, 4G) as WB and the second MTRR describes [3.5G, 4G) as UC; WB+UC=UC, so the resulting memory map would be as needed, but in this configuration our attempts to map LFB at (say) 0xE8000000 as WC would be ignored, WB+UC+WC is still UC. So we must keep top of 4G memory not covered by MTRRs, using three WB MTRRs [0,2G) + [2G,3G) + [3G,3.5G), this gives the same memory map, but allows to add further entries. See mtrrtest.asm for detailed input/output from real hardware+BIOS.

Source: core/mtrr.inc:129

◆ mtrr_validate()

void mtrr_validate ( )

If MTRRs are configured improperly, this is not obvious to the user; everything works, but the performance can be horrible. Try to detect this and let the user know that the low performance is caused by some problem and is not a global property of the system. Let's hope he would report it to developers...