Subject: Re: [linux-audio-user] Low-Latency 2.4.x with ALSA
From: Patrick Shirkey (pshirkey_AT_boosthardware.com)
Date: Mon Jul 22 2002 - 05:23:59 EEST
Joseph Zitt wrote:
> I'm going through the steps in the Low-Latency 2.4.x with ALSA
> mini-HOWTO.
> It's quite good and clear, but a few issues have come up:
>
> 1) The document recommends doing the patch with the following:
>
> cd /usr/src/
> patch -p0 < /dir/where/you/put/2.4.x-low-latency.patch
>
> However, as mentioned in earlier messages, it looks like doing
>
> cd /usr/src/linux
> patch -p1 < /dir/where/you/put/2.4.x-low-latency.patch
>
> is more effective, since it avoids problems with a pathname that is
> otherwise hardwired into the patch code.
>
I'll make a note.
> 2) The document points out places to change configuration options. In
> doing a "make xconfig", some of these places are not visible, and it
> would be worth noting the path down to them and undocumented additional
> needed steps:
>
While it's still fresh in your memory do you mind writing down the steps?
> a) To enable "Control low latency with sysctl", I first had to enable
> "Low latency scheduling" above it.
>
Well that's what the help option says to do right?
> b) "IDE, ATA, and ATAPI block devices" is in a sub-window under
> "ATA/IDE/MFM/RLL support" (surprisingly not, as I'd first guessed, under
> the obvious "Block devices").
>
> 3) Looking at the description of the EXTRAVERSION information, I
> couldn't quite figure out how the value in the example mapped to what it
> was intended to describe.
>
Yes.
> 4) And the one that has me stuck now: while the document has clear
> instructions for setting up booting with LILO, I'm using GRUB. I'm not
> seeing how to set up grub to use the new kernel, or whether the existing
> setup will do the right thing. The /boot/grub/grub.conf file includes
> references to files that have not changed or been updated, and I'm not
> clear on whether it will work. Since I don't know whether continuing
> without changing things there will result in an unbootable system, I'm
> loth to experiment.
>
It would be good to include something on using grub.
I found these pages with google
http://www.linuxgazette.com/issue64/kohli.html
http://www.gnu.org/manual/grub/html_mono/grub.html
---- The best use of GRUB is that you can load any kernel on any partition right out of the box. For example, if you forget adding the newly compiled kernel to the list, you would normally need to boot, add it to the list and then reboot to use it. But with GRUB, you can simply use the shell and load the desired kernel image. ----I use lilo so someone else will have to help you or you will have to do some more reading.
> FWIW, my grub.conf has the following: > > # grub.conf generated by anaconda > # > # Note that you do not have to rerun grub after making changes to this > # file NOTICE: You do not have a /boot partition. This means that > # all kernel and initrd paths are relative to /, eg. > # root (hd0,6) > # kernel /boot/vmlinuz-version ro root=/dev/hda7 > # initrd /boot/initrd-version.img > #boot=/dev/hda > default=1 > timeout=10 > splashimage=(hd0,6)/boot/grub/splash.xpm.gz > title Red Hat Linux (2.4.18-3) > root (hd0,6) > kernel /boot/vmlinuz-2.4.18-3 ro root=/dev/hda7 > initrd /boot/initrd-2.4.18-3.img > title Red Hat Linux (New Kernel) > root (hd0,6) > kernel /boot/vmlinuz ro root=/dev/hda7 > initrd /boot/initrd-2.4.18-3.img > title Red Hat Linux (2.4.18-3) > root (hd0,6) > kernel /boot/vmlinuz-2.4.18-3 ro root=/dev/hda7 > initrd /boot/initrd-2.4.18-3.img > title Windows 98 > rootnoverify (hd0,0) > chainloader +1 > > (Yeah, I never use the first and third ones, and am not sure why they're > there--but, again, worrying about breaking something into unbootability > if I mess with the grub.conf incorrectly.) > > After doing the suggested > > # > > cp arch/i386/boot/bzImage /boot/bzImage-2.4.18 > cp System.map /boot/System.map > > I now have the following in /boot: > > -rw-r--r-- 1 root root 5824 Jun 24 2001 boot.b > -rw-r--r-- 1 root root 1105371 Jul 21 15:07 bzImage-2.4.18 > -rw-r--r-- 1 root root 612 Jun 24 2001 chain.b > -rw-r--r-- 1 root root 39947 Apr 18 04:45 config-2.4.18-3 > drwxr-xr-x 2 root root 4096 Jun 4 11:16 grub > -rw-r--r-- 1 root root 126072 Jun 4 11:16 > initrd-2.4.18-3.img > -rw-r--r-- 1 root root 473 May 30 23:01 kernel.h > -rw-r--r-- 1 root root 23108 Jun 24 2001 message > lrwxrwxrwx 1 root root 20 Jun 4 11:16 module-info -> > module-info-2.4.18-3 > -rw-r--r-- 1 root root 14431 Apr 18 04:45 > module-info-2.4.18-3 > -rw-r--r-- 1 root root 640 Jun 24 2001 os2_d.b > lrwxrwxrwx 1 root root 19 Jun 4 11:16 System.map -> > System.map-2.4.18-3 > -rw-r--r-- 1 root root 529786 Jul 21 15:39 > System.map-2.4.18-3 > -rwxr-xr-x 1 root root 3414559 Jun 4 09:43 vmlinux > -rwxr-xr-x 1 root root 2835238 Apr 18 04:45 vmlinux-2.4.18-3 > lrwxrwxrwx 1 root root 16 Jun 4 11:16 vmlinuz -> > vmlinuz-2.4.18-3 > -rw-r--r-- 1 root root 1030147 Apr 18 04:45 vmlinuz-2.4.18-3 > > All the "2.4.18-3" stuff is from what was in there before I started. I > find it particularly odd that copying the new System.map file into this > directory didn't change the file from being a link to an old value, > though cp gave no error. >
rm -rf /boot/System,map cp /usr/src/linux/System.map /boot/
You can do the same for the bzImage and it works.
> I haven't gotten to the modutils section yet, but I'm seeing that I'll > have a few questions, such as a best source for the modutils package, > and good test arguments to see if modprobe or insprob were successful. >
You should definitely have modutils working on your system already.
do insmod -v and check the version number against the one in the howto. It is still relevant.
> I also see that it says to do > > cd /usr/src/linux > make modules; make modules_install >
If you have done it once then it's unnecessary to do it again. I'll find the reference and remove it.
> after booting into the new kernel, though it said to do so earlier, too, > in building the kernel. It's conceivable that it has to be done twice, > but I figure it's worth doublechecking. > > ... and eventually I'll actually get to the point where I install > ALSA... >
-- Patrick Shirkey - Boost Hardware Ltd. For the discerning hardware connoisseur http://www.boosthardware.com http://www.boosthardware.com/LAU/guide/ ========================================
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