kernel 4.8.9_64
slackware 14.1
SD Host controller: O2 Micro, Inc. Device 8520 (rev 01)

I insert an SD card and get this:
fdisk -l does not see /dev/sdc
The machine slows down, has to be rebooted to function properly again.

Does anyone know how to overcome the objection to SD cards ?

Is this a good sdcard? Does it work elsewhere? Is it a usb-1.x, usb-2.x or usb-3.x socket?

It looks to me like a hardware over-current reaction, where irq 19 is mapped to that usb. The usable current in usb 1-3 sockets varies, usb-1.x being 100mA, usb-3.x being 500mA, and usb-2.x in between.
If it is overcurrent, the sdcard is toast.

1 members found this post helpful.

It is a perfectly good card; in fact I tried three different ones.
They all work under kernel 2.6.33 Slackware 13.1

kernel 2.6.33?

That's old. Does it know about usb 2, or 3? What usb modules load? Is the hardware old? To solve your problems, answers are needed, because your information is insufficient.

1 members found this post helpful.

What is insufficient is your reading and comprehension (obviously a victim of public education)

Do you know anything about Linux ? about kernel 4.8.9 and its hatred towards sdcards ? (windows has no objection to sdcards)
Have you ever compiled a kernel ?
Do you know anything about Slackware ? Slackware 14.1 ?

I'm not responding in kind to that. Just about every detail is wrong. Being an ex Mensa member and privately educated, my reading and comprehension are not limited. I've been using linux since the 1990s,I know plenty about linux, I've been running slackware nearly 10 years except for a dalliance with slamd-12.2. I had 2 boxes running 14.1 when it was current and make a practise of compiling my own kernels.

1 members found this post helpful.

789, please use wording that conforms to a professional businesslike standard. Personal attacks are not allowed. I'd further ask that you please edit your post.

An idea to your issue may be this.

"
Using the kernel parameter "noirqdebug" appears to remedy the problem.

Note, this problem has been observed on debian as well. I believe that it concerns the kernel and/or the manufacturer's implementation of PCI PNP. "

https://forums.centos.org/viewtopic.php?t=5649

'noirqdebug' or 'irqpoll' did not work in my case, "fdisk -l" still does not see the SDCARD. The only change is that kernel parameter (if added at boot time, using "tab") stopped the "disabling irq 19" response to inserting an SDCARD ---the machine now does not slow down, it doesn't need to be rebooted.

At least we now know that my compiling the kernel is not the cause of the problem (of not recognizing SD cards
__________________
As for your guru friend: you should direct your response to him ---I merely asked a question if he knew anything about linux, because his reply gives the impression that he did not comprehend what I posted (if he read the question at all)

10,000 posts ?! no girlfriend, no wife ? now life ? no job ?

I watch the news as little as possible. Politicians on all sides screaming this and that. Once in a while I use different forums and the people are openly insulting each other. Guess it's part of the times maybe. Fortunately LQ has been trying to maintain a place that is open and welcoming to members. The general areas of LQ are much more lax. I ask you again to try to use this site for what is it. Free help from volunteers. Please use the technical forums for technical issues.


The people who are members here are mostly laid back for of people who volunteer their time to assist on questions. Some get to do it from work and some may be working from home and select the questions they try to help on. I's assume that many use this as one of their hobbies. I get to do this from work if everything is going OK.

Problem solved

There is nothing wrong with linux-4.8.9, there is no bug; the cause of the predicament was my compiling .
After several trys and fails, I managed to make a .config which not only compiles a kernel and modules that recognize SDcard, but as a side effect, compiles dell-laptop.c, dell-smbios.c, dell-smm-hwmon.c modules, too.

Now I can even change the kbd_backlight timeout.


Without any help from these gurus and cadets (so much for 10,000 posts)


I don't know what I did right this time, but I noticed (in conky) that the IRQ assignment seems to be different.