Date: Mon, 21 Jul 1997 15:21:06 -0700 (PDT) From: Vinay Bannai <vinay@agni.nuko.com> To: se@freebsd.org (Stefan Esser) Cc: freebsd-hackers@freebsd.org Subject: Re: Kernel panic in driver probe() routine Message-ID: <199707212221.PAA03602@agni.nuko.com> In-Reply-To: <19970722000635.41795@mi.uni-koeln.de> from "Stefan Esser" at "Jul 22, 97 00:06:35 am"
next in thread | previous in thread | raw e-mail | index | archive | help
According to Stefan Esser:
> On Jul 21, Vinay Bannai <vinay@agni.nuko.com> wrote:
> > Actually it was in my attach() routine. Here it is:
> > I am freeing up my memory towards the end under the label fail
>
> Ahhh, yes, I see ...
>
> But you are freeing memory not obtained through a call to
> malloc(), and that is generally considered a bad thing :)
>
> > if (!pci_map_mem(config_id, CYCLONE_PCI_MMRR_REG,
> > (vm_offset_t *)&vaddr, (vm_offset_t *)&paddr)) {
> > printf("cyclone%d: couldn't map memory\n", unit);
> > goto fail;
>
> > fail:
> > if (vaddr)
> > free((void *)vaddr, M_DEVBUF);
>
> Here vmaddr did not point to a memory region allocated by
> malloc, but to one that got a virtual to physical mapping
> established by a call to pmap_mapdev (/sys/i386/i386/pmap.c).
STefan,
You are correct. I just looked at the code for pmap.c and it in turn calls
kern_alloc_pageable(). I don't exaclty understand all the stuff about maps
and submaps, but seems like the virtual memory is not coming from the
place where malloc() gets it!!
> You may want to ask David Greenman about how to release
> such a mapping. I didn't bother, since the page table entry
> created for the device consumes only 4 bytes per 4KB page
> you allocated, and the code to free the page table entries
> is likely to be much larger, except for large regions ...
>
> Regards, STefan
Yup. I will just ignore it for the time being and bother DG later on when
I start running into DMA problems. :-)
The PCI device that I am interfacing is capable of doing lot more things
(since it has got a i960 processor wiht 4M of RAM). But initially I want
to test by passing back and forth to the card some packets of fixed
size. Are there any guidelines as to how much memory I should allocate for
the Rx and Tx buffers? I am bad at picking numbers :-)
Vinay
--
Vinay Bannai E-mail: vinay@agni.nuko.com
(408)-526-0280 x 275 (Work) http://agni.nuko.com/~vinay
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199707212221.PAA03602>