xref: /src/sys/arch/arc/TODO

$NetBSD: TODO,v 1.17 2003/04/06 17:48:51 tsutsui Exp $

To do list (in some particular order)
XXX some entries might be obsolete.

    o   Boot. Standalone boot program to load ELF kernels instead of
	booting ECOFF kernels directly.
	(maybe sgimips/stand would help, but annoying buggy ARC BIOS)

    o	sysinst
	maybe MD fdisk partitioning support is required to load files
	from FAT partition on ARC BIOS prompt.

    o	install notes


    o	use MI driver

	-   use MI ncr53c9x driver instead of home grown asc
	    XXX patch is available. needs testers

	-   make fd driver MI, and share it with other ports
	    (contact christos about MI fd driver)

	-   use MI bha driver instead of home grown btl
	    XXX needs fixes of DESKstation support

    o	VXL framebuffer support (Magnum, RISCstation 2200)

    o	com_jazzio.c
	-   clock handling clean up (obtain from ARC BIOS)
	-   fifo disabling may be only needed on some Magnum?

    o	remove pccons and switch to wscons completely
	(XXX what's the problem to remove pccons?)

    o	AD1848 audio support

    o	missing MI devices
		ses?, vcoda, ...


    o	Xserver

	-   VXL		Magnum, RISCstation 2200
	-   vga/S3	PICA, Image RISCstation - OpenBSD's?
	-   vga/cirrus	RISCserver 2200, Express5800/240 R4400 EISA
	-   vga/???	DESKstation Tyne, rPC44
	-   TGA		RISCstation 2250, Express5800/230 R4400 PCI

    o   Find out why bitmap load to S3-928 flashes screen. (X server)
	Know why (enable linear mode). Need S3 info.


    o	repair DESKstation support
	-   requires bounce buffer bus_dma for Tyne
		XXX - too small bounce buffer size (128KB)

    o	Olivetti M700 support

    o	NEC Express5800/230 R10000 PCI (NEC-JC95) support
	(needs MI R10000 support)

    o	SNI RM200PCI/RM300/RM400/RM600 support


    o	parse ARC BIOS configuration information and use it

    o	increase MAXPHYS to 64KB
	(XXX why is it limited to 32KB?)

    o	fix kernel start address
	(maybe requires bootloader support)

    o	allocate PICA_TL_BASE dynamically

    o	remove inb/outb

    o	remove UADDR

    o	fix mem_clusters[] usage.

    o	intrcnt[] name cleanup, use MI evcnt(9)

    o	test and merge soren's clean up about proc0.p_addr.

    o	redesign interrupt handler framework.
	i/o bus devices should have sane IPL, but currently doesn't.

	also, current MIPS interrupt handler has overblocking and
	other problems as follows:

	-   SR_INT_IE should be enabled before calling hardclock().
	    Since this is not done currently, spllowersoftclock()
	    on hardclock() doesn't have effect, and softclock() is
	    handled with all interrupt disabled in this case.
		-> overblocking, possibly causes missing hardclock()

	-   MIPS3_CLKF_BASEPRI() doesn't work correctly,
	    when MIPS_INT_MASK_5 (== MIPS_INT_MASK_CLOCK) is disabled.
		-> micro optimization on hardclock() doesn't work.
		   but currently this may make hardclock() latency better
		   due to above SR_INT_IE problem.
	    s/MIPS_INT_MASK/MIPS3_INT_MASK/ makes this work, although tricky.

	-   if (ipending & INT_MASK_REAL_DEV) == 0,
	    softnet() and softclock() are handled with all interrupt disabled.
		-> overblocking, possibly causes missing hardclock()

	-   softclock() is handled with softnet() disabled.
		-> slightly overblocking

	-   `netisr' handling in netintr() implies potential race condition.
	    The access to `netisr' should be protected by splnet().
	    Currently this is not real problem due to above overblocking.

	    `ssir' handling on many mips ports has same problem.
	    It should be protected by splnet() or splserial() or splhigh()
	    (depends on the highest interrupt level which sets `ssir').
	    Since `ssir' is accessed not only by setsoftnet() but also
	    by setsoft(), setsoftnet() should protect `ssir' by splserial()
	    or something. (i.e. priority level which setsoft() will be called)
	    Probably, it is better to split `ssir' variable for each
	    priority level.
	    Also, _clearsoftintr() should be called before `ssir' access.
	    currently this is not real problem due to above overblocking.

	-   INT_MASK_REAL_DEV should be removed

	-   make CLKF_INTR() work.

	-   generic software interrupt
	    (see algor, mipsco, pmax etc.)

	-   major rework, possibly by software emulated spl.
		splserial()/splsoftserial()

    o	it is better to always disable MIPS_INT_MASK_CLOCK.
	those are the points which should be fixed:
	mips_idle: li t0, (MIPS_INT_MASK | MIPS_SR_INT_IE)
	machdep.c: curpcb->pcb_context[11] = MIPS_INT_MASK | MIPS_SR_INT_IE;
	spl0()
	splnone()

	-   MIPS_INT_MASK_CLOCK should be removed in someway

    o	XXX at least 2000/06/07 version is already quite unstable
	on PICA and NEC Image RISCstation. (but almost OK on Magnum)
	Userland commands dumps	core randomly.
	This version is before _MIPS_PADDR_T_64BIT changes
	and MIPS3_TLB_WIRED_UPAGES changes.	

	"vm_page_zero_enable = FALSE" makes this problem disappeared.
	(vm_page_zero_enable = FALSE by default on all archs w/ UBC, now)

	currently, page zero in the idle loop is also disabled on
	untested platforms like DESKstation rPC44/Tyne and SNI for safety.

	    XXX what's the current status of uvm_pageidlezero()?


    o	resolve "XXX"


(following entries might be MI MIPS items)

    o	Move the RO and WIRED attribute from the pte to the pv table.
	This saves four instructions in the tlb miss handler.

    o   Can we have 32 double registers?

    o	64bit kernel/userland

    o	fix implementation of DELAY(), clean up clock implementation

    o	omit __SWAP_BROKEN in <mips/types.h>

    o	clean up ALEAF/NLEAF/NON_LEAF/NNON_LEAF in userland.

Lots of other things.....