PCMCIA product id strings -> hashes generation at compilation
time? [Was: Re: [patch 14/38] pcmcia: id_table for wavelan_cs]
Benjamin Herrenschmidt
benh at kernel.crashing.org
Wed Mar 9 00:45:09 EST 2005
On Wed, 2005-03-09 at 00:16 +0100, Dominik Brodowski wrote:
> > Dominik Brodowski <linux at dominikbrodowski.net> wrote:
> > >
> > > Most pcmcia devices are matched to drivers using "product ID strings"
> > > embedded in the devices' Card Information Structures, as "manufactor ID /
> > > card ID" matches are much less reliable. Unfortunately, these strings cannot
> > > be passed to userspace for easy userspace-based loading of appropriate
> > > modules (MODNAME -- hotplug), so my suggestion is to also store crc32 hashes
> > > of the strings in the MODULE_DEVICE_TABLEs, e.g.:
> > >
> > > PCMCIA_DEVICE_PROD_ID12("LINKSYS", "E-CARD", 0xf7cb0b07, 0x6701da11),
> >
> > What is the difficulty in passing these strings via /sbin/hotplug arguments?
>
> The difficulty is that extracting and evaluating them breaks the wonderful
> bus-independent MODNAME implementation for hotplug suggested by Roman Kagan
> ( http://article.gmane.org/gmane.linux.hotplug.devel/7039 ), and that these
> strings may contain spaces and other "strange" characters. The latter may be
> worked around, but the former cannot. /etc/hotplug/pcmcia.agent looks really
> clean because of this MODNAME implementation:
Same goes with Open Firmware match strings that we are about to pass
down to userspace as well. Hotplug will have to learn to deal with
those.
> #!/bin/sh
>
> cd /etc/hotplug
> . ./hotplug.functions
>
> if [ "$ACTION" = "" ]; then
> mesg Bad PCMCIA agent invocation, no action
> exit 1
> fi
>
> case $ACTION in
>
> add)
> modprobe $MODNAME
>
> ... work around some exotic buggy PCMCIA hardware ...
> ...
>
> and I would very much like to avoid breaking the line "modprobe $MODNAME".
>
> On Tue, Mar 08, 2005 at 02:54:57PM -0800, Linus Torvalds wrote:
> >
> >
> > On Tue, 8 Mar 2005, Dominik Brodowski wrote:
> > >
> > > Unfortunately, these strings cannot
> > > be passed to userspace for easy userspace-based loading of appropriate
> > > modules (MODNAME -- hotplug), so my suggestion is to also store crc32 hashes
> > > of the strings in the MODULE_DEVICE_TABLEs, e.g.:
> > >
> > > PCMCIA_DEVICE_PROD_ID12("LINKSYS", "E-CARD", 0xf7cb0b07, 0x6701da11),
> >
> > Hmm.. I'm with Andrew on this one - I'd much rather really pass them to
> > user space as strings. We already pass a number of strings as environment
> > variables.
> >
> > In fact, what's wrong with DEVPATH? Which we already expose as the
> > NAME=xxx environment variable. So if the kboject associated with a device
> > has has this string associated with its name (which it should)
> drivers/base/core.c::device_add()
> kobject_set_name(&dev->kobj, "%s", dev->bus_id);
> and the bus_id isn't the device's name for common buses.
>
> Nontheless, the strings _are_ exported at DEVPATH/prod_id[1-4], but for the
> reasons mentioned above I'd prefer not to use them.
>
>
> On Tue, Mar 08, 2005 at 12:34:26PM -0800, Andrew Morton wrote:
> > > ...
> > > To make the life easier for device driver authors,
> > > - a big warning is put into dmesg if a pcmcia driver is inserted
> > > into the kernel and the hash mentioned in PCMCIA_DEVICE_PROD_ID()
> > > is incorrect,
> >
> > As long as the kernel shouts loudly at the driver developer at
> > development-time, and that shouting mentions a bit of documentation in
> > Documentation/somewhere, I expect we'll be OK.
>
> Andrew, please apply this patch on top of 2.6.11-mm2, if you and Linus still
> agree:
>
>
> Add some information useful for PCMCIA device driver authors to
> Documentation/pcmcia/, and reference it in dmesg in case of hash mismatches.
>
> Also add a reference to pcmciautils to Documentation/Changes. With recent
> changes, you don't need to concern yourself with pcmcia-cs even if you have
> PCMCIA hardware, so the example above the list needed to be adapted as well.
>
> Signed-off-by: Dominik Brodowski <linux at dominikbrodowksi.net>
> Index: 2.6.11+/Documentation/Changes
> ===================================================================
> --- 2.6.11+.orig/Documentation/Changes 2005-03-08 23:23:30.000000000 +0100
> +++ 2.6.11+/Documentation/Changes 2005-03-08 23:23:33.000000000 +0100
> @@ -44,9 +44,9 @@
>
> Again, keep in mind that this list assumes you are already
> functionally running a Linux 2.4 kernel. Also, not all tools are
> -necessary on all systems; obviously, if you don't have any PCMCIA (PC
> -Card) hardware, for example, you probably needn't concern yourself
> -with pcmcia-cs.
> +necessary on all systems; obviously, if you don't have any ISDN
> +hardware, for example, you probably needn't concern yourself with
> +isdn4k-utils.
>
> o Gnu C 2.95.3 # gcc --version
> o Gnu make 3.79.1 # make --version
> @@ -57,6 +57,7 @@
> o jfsutils 1.1.3 # fsck.jfs -V
> o reiserfsprogs 3.6.3 # reiserfsck -V 2>&1|grep reiserfsprogs
> o xfsprogs 2.6.0 # xfs_db -V
> +o pcmciautils 001
> o pcmcia-cs 3.1.21 # cardmgr -V
> o quota-tools 3.09 # quota -V
> o PPP 2.4.0 # pppd --version
> @@ -186,13 +187,20 @@
> work correctly with this version of the XFS kernel code (2.6.0 or
> later is recommended, due to some significant improvements).
>
> +PCMCIAutils
> +-----------
> +
> +PCMCIAutils replaces pcmcia-cs (see below). It properly sets up
> +PCMCIA sockets at system startup and loads the appropriate modules
> +for 16-bit PCMCIA devices if the kernel is modularized and the hotplug
> +subsystem is used.
>
> Pcmcia-cs
> ---------
>
> PCMCIA (PC Card) support is now partially implemented in the main
> -kernel source. Pay attention when you recompile your kernel ;-).
> -Also, be sure to upgrade to the latest pcmcia-cs release.
> +kernel source. The "pcmciautils" package (see above) replaces pcmcia-cs
> +for newest kernels.
>
> Quota-tools
> -----------
> @@ -349,9 +357,13 @@
> --------
> o <ftp://oss.sgi.com/projects/xfs/download/>
>
> +Pcmciautils
> +-----------
> +o <ftp://ftp.kernel.org/pub/linux/utils/kernel/pcmcia/>
> +
> Pcmcia-cs
> ---------
> -o <ftp://pcmcia-cs.sourceforge.net/pub/pcmcia-cs/pcmcia-cs-3.1.21.tar.gz>
> +o <http://pcmcia-cs.sourceforge.net/>
>
> Quota-tools
> ----------
> Index: 2.6.11+/Documentation/pcmcia/devicetable.txt
> ===================================================================
> --- 2.6.11+.orig/Documentation/pcmcia/devicetable.txt 2005-03-08 22:41:21.540138608 +0100
> +++ 2.6.11+/Documentation/pcmcia/devicetable.txt 2005-03-08 23:57:46.000000000 +0100
> @@ -0,0 +1,64 @@
> +Matching of PCMCIA devices to drivers is done using one or more of the
> +following criteria:
> +
> +- manufactor ID
> +- card ID
> +- product ID strings _and_ hashes of these strings
> +- function ID
> +- device function (actual and pseudo)
> +
> +You should use the helpers in include/pcmcia/device_id.h for generating the
> +struct pcmcia_device_id[] entries which match devices to drivers.
> +
> +If you want to match product ID strings, you also need to pass the crc32
> +hashes of the string to the macro, e.g. if you want to match the product ID
> +string 1, you need to use
> +
> +PCMCIA_DEVICE_PROD_ID1("some_string", 0x(hash_of_some_string)),
> +
> +If the hash is incorrect, the kernel will inform you about this in "dmesg"
> +upon module initialization, and tell you of the correct hash.
> +
> +You can determine the hash of the product ID strings by running
> +"pcmcia-modalias %n.%m" [%n being replaced with the socket number and %m being
> +replaced with the device function] from pcmciautils. It generates a string
> +in the following form:
> +pcmcia:m0149cC1ABf06pfn00fn00pa725B842DpbF1EFEE84pc0877B627pd00000000
> +
> +The hex value after "pa" is the hash of product ID string 1, after "pb" for
> +string 2 and so on.
> +
> +Alternatively, you can use this small tool to determine the crc32 hash.
> +simply pass the string you want to evaluate as argument to this program,
> +e.g.
> +$ ./crc32hash "Dual Speed"
> +
> +-------------------------------------------------------------------------
> +/* crc32hash.c - derived from linux/lib/crc32.c, GNU GPL v2 */
> +#include <string.h>
> +#include <stdio.h>
> +#include <ctype.h>
> +#include <stdlib.h>
> +
> +unsigned int crc32(unsigned char const *p, unsigned int len)
> +{
> + int i;
> + unsigned int crc = 0;
> + while (len--)
> + crc ^= *p++;
> + for (i = 0; i < 8; i++)
> + crc = (crc >> 1) ^ ((crc & 1) ? 0xedb88320 : 0);
> + }
> + return crc;
> +}
> +
> +int main(int argc, char **argv) {
> + unsigned int result;
> + if (argc != 2) {
> + printf("no string passed as argument\n");
> + return -1;
> + }
> + result = crc32(argv[1], strlen(argv[1]));
> + printf("0x%x\n", result);
> + return 0;
> +}
> Index: 2.6.11+/Documentation/pcmcia/driver-changes.txt
> ===================================================================
> --- 2.6.11+.orig/Documentation/pcmcia/driver-changes.txt 2005-03-08 22:41:21.540138608 +0100
> +++ 2.6.11+/Documentation/pcmcia/driver-changes.txt 2005-03-09 00:01:07.000000000 +0100
> @@ -0,0 +1,51 @@
> +This file details changes in 2.6 which affect PCMCIA card driver authors:
> +
> +* in-kernel device<->driver matching
> + PCMCIA devices and their correct drivers can now be matched in
> + kernelspace. See 'devicetable.txt' for details.
> +
> +* Device model integration (as of 2.6.11)
> + A struct pcmcia_device is registered with the device model core,
> + and can be used (e.g. for SET_NETDEV_DEV) by using
> + handle_to_dev(client_handle_t * handle).
> +
> +* Convert internal I/O port addresses to unsigned long (as of 2.6.11)
> + ioaddr_t should be replaced by kio_addr_t in PCMCIA card drivers.
> +
> +* irq_mask and irq_list parameters (as of 2.6.11)
> + The irq_mask and irq_list parameters should no longer be used in
> + PCMCIA card drivers. Instead, it is the job of the PCMCIA core to
> + determine which IRQ should be used. Therefore, link->irq.IRQInfo2
> + is ignored.
> +
> +* client->PendingEvents is gone (as of 2.6.11)
> + client->PendingEvents is no longer available.
> +
> +* client->Attributes are gone (as of 2.6.11)
> + client->Attributes is unused, therefore it is removed from all
> + PCMCIA card drivers
> +
> +* core functions no longer available (as of 2.6.11)
> + The following functions have been removed from the kernel source
> + because they are unused by all in-kernel drivers, and no external
> + driver was reported to rely on them:
> + pcmcia_get_first_region()
> + pcmcia_get_next_region()
> + pcmcia_modify_window()
> + pcmcia_set_event_mask()
> + pcmcia_get_first_window()
> + pcmcia_get_next_window()
> +
> +* device list iteration upon module removal (as of 2.6.10)
> + It is no longer necessary to iterate on the driver's internal
> + client list and call the ->detach() function upon module removal.
> +
> +* Resource management. (as of 2.6.8)
> + Although the PCMCIA subsystem will allocate resources for cards,
> + it no longer marks these resources busy. This means that driver
> + authors are now responsible for claiming your resources as per
> + other drivers in Linux. You should use request_region() to mark
> + your IO regions in-use, and request_mem_region() to mark your
> + memory regions in-use. The name argument should be a pointer to
> + your driver name. Eg, for pcnet_cs, name should point to the
> + string "pcnet_cs".
> Index: 2.6.11+/drivers/pcmcia/ds.c
> ===================================================================
> --- 2.6.11+.orig/drivers/pcmcia/ds.c 2005-03-08 23:23:30.000000000 +0100
> +++ 2.6.11+/drivers/pcmcia/ds.c 2005-03-08 23:59:01.000000000 +0100
> @@ -262,8 +262,6 @@
> }
> EXPORT_SYMBOL(cs_error);
>
> -#ifdef CONFIG_PCMCIA_DEBUG
> -
>
> static void pcmcia_check_driver(struct pcmcia_driver *p_drv)
> {
> @@ -284,6 +282,9 @@
> "product string \"%s\": is 0x%x, should "
> "be 0x%x\n", p_drv->drv.name, did->prod_id[i],
> did->prod_id_hash[i], hash);
> + printk(KERN_DEBUG "pcmcia: see "
> + "Documentation/pcmcia/devicetable.txt for "
> + "details\n");
> }
> did++;
> }
> @@ -291,12 +292,6 @@
> return;
> }
>
> -#else
> -static inline void pcmcia_check_driver(struct pcmcia_driver *p_drv) {
> - return;
> -}
> -#endif
> -
>
> #ifdef CONFIG_PCMCIA_LOAD_CIS
>
> -
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--
Benjamin Herrenschmidt <benh at kernel.crashing.org>
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