Re: Finding the mmc cards
I'm interested to hear thatanything outside of the SD cardhas a choice in the matter. There was a time when hardware write-protection of this kind was exactly that: harware-enforced write-protection. I would have expected that, if I put the switch on an SD card into the "write-protected" position, the card itself would disable or ignore write operations (by, for example, disabling whatever line/signal is used to perform the write operation). David Hazel On 8/29/07, David Hazel [EMAIL PROTECTED] wrote: - whether write protected (yes, you can write-protect an SD card) Yes, but the Nokia's do not support or honor that switch. ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
Re: Finding the mmc cards
Hi, MMC_MOUNTPOINT variable was present on 770 already and the device had one (external) mmc slot only. N800 added a second memory card slot (the internal one) and respective variable... -Markku- David Hazel wrote: You can also use the environment variables MMC_MOUNTPOINT and INTERNAL_MMC_MOUNTPOINT, but then you have to make sure that they are always set correctly in your environment. (I don't think using environment variables for this kind of system information is a good idea.) Those environment variables seem oddly inconsistent to an ex-VMS man like me. Why not EXTERNAL_MMC_MOUNTPOINT and INTERNAL_MMC_MOUNTPOINT? Otherwise it's necessary to remember which one the unqualified MMC_MOUNTPOINT refers to (e.g. by remembering that the other one starts with INTERNAL rather than EXTERNAL - which itself is counter-intuitive, as I would expect the internal one to be the more important and therefore the unqualified one). ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
Re: Finding the mmc cards
On 8/30/07, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: I'm interested to hear that anything outside of the SD card has a choice in the matter. There was a time when hardware write-protection of this kind was exactly that: harware-enforced write-protection. I would have expected that, if I put the switch on an SD card into the write-protected position, the card itself would disable or ignore write operations (by, for example, disabling whatever line/signal is used to perform the write operation). Nope, the specs leave it up to the device to implement, kind of like the old notch on floppies ;-) From the Nokia n800 user manual: This device does not support the write protection feature of SD cards. I don't believe the write protection switch was part of the original MMC card design specs was it? I'm not in the loop but it's only recently I started seeing cards with the switch. I'm assuming it sets some bit somewhere to tell the hardware Hey, leave me alone which Maemo promptly ignores. ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
Re: Finding the mmc cards
On 8/29/07, Tony Maro [EMAIL PROTECTED] wrote: After our thread some weeks ago regarding reading the serial number from a MMC card, I've since implemented detection of the MMC card's presence by the existence of those same files. I know my solution works on my device perfectly. Hello I use cat /proc/partitions on my desktop system to see what the partition are available on my desktop system bus perhaps listening to dbus or kernel events is the right way :) looking at mtab or the output of mount will also help greetings I figure it's probably a bad decision, because the architecture could change somewhat with the next hardware or software release. Can someone tell me, is there an approved / documented way of identifying the location of any MMC cards currently installed? I've noticed you can't simply look for /media/mmcX because that directory will exist even if there is no card inserted. Also, what determines MMC1 vs MMC2 as the card's path for internal/external? Is it possible these paths would change at some date? I know some Linux distro's with SATA drives had a problem with the drives changing their /dev/sdX path every reboot. I know that MY Nokia isn't doing anything similar, but I figure it's possible that my /media/mmc1 might be internal, but for someone else it could be the external slot - or maybe in the next hardware revision or something. I did find the alias names located in the /sys/ path that specify internal is for one and external or removable or something for the other. Also, are the names and paths the same for the 770's? Since I have an n800 I don't know. I'm hesitant to read too much data from /sys/ because it all looks _so_ Maemo-specific I wonder if I will tie my code too closely to one hardware revision. Just looking for the most _compatible_ way to identify if/when and where a media card is present. And as usual, from Python. Thanks, Tony ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
RE: Finding the mmc cards
I agree that assuming mmc1 and mmc2 is potentially dangerous. In an answer to my original question on this subject, someone suggested that mmc0 and mmc1 were the correct names, whereas in my Scratchbox environment they are mmc1 and mmc2. Consequently, when I was implementing a scan for memory cards, I opted to look in the /media folder for files whose names begin "mmc", and to assume that any such file I find might be a memory card. This appears to work (in the test/development environment), but personally I hate making those kinds of assumptions. I would far rather have a definitive statement from someone to the effect that "if you do X, this will guarantee to find the memory cards and nothing else". For me, this is particularly important, as my application will be sold commercially and needs to work under all circumstances. David Hazel After our thread some weeks ago regarding reading the serial number from a MMC card, I've since implemented detection of the MMC card's presence by the existence of those same files. I know my solution works on my device perfectly. I figure it's probably a bad decision, because the architecture could change somewhat with the next hardware or software release.Can someone tell me, is there an approved / documented way of identifying the location of any MMC cards currently installed? I've noticed you can't simply look for /media/mmcX because that directory will exist even if there is no card inserted. Also, what determines MMC1 vs MMC2 as the card's path for internal/external? Is it possible these paths would change at some date? I know some Linux distro's with SATA drives had a problem with the drives changing their /dev/sdX path every reboot. I know that MY Nokia isn't doing anything similar, but I figure it's possible that my /media/mmc1 might be internal, but for someone else it could be the external slot - or maybe in the next hardware revision or something. I did find the alias names located in the /sys/ path that specify "internal" is for one and "external" or removable or something for the other. Also, are the names and paths the same for the 770's? Since I have an n800 I don't know. I'm hesitant to read too much data from /sys/ because it all looks _so_ Maemo-specific I wonder if I will tie my code too closely to one hardware revision. Just looking for the most _compatible_ way to identify if/when and where a media card is present.And as usual, from Python.Thanks,Tony ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
Re: Finding the mmc cards
Hi, Please file a documentation bug into Maemo Bugzilla. We need this documented. Handling of removable medias, especially with file systems as easily corrupted as FAT, needs special care from applications (stop using files when pre-unmount message is delivered on them so that unmounts succeed, do better error handling etc.) - Eero ext [EMAIL PROTECTED] wrote: I agree that assuming mmc1 and mmc2 is potentially dangerous. In an answer to my original question on this subject, someone suggested that mmc0 and mmc1 were the correct names, whereas in my Scratchbox environment they are mmc1 and mmc2. Consequently, when I was implementing a scan for memory cards, I opted to look in the /media folder for files whose names begin mmc, and to assume that any such file I find might be a memory card. This appears to work (in the test/development environment), but personally I hate making those kinds of assumptions. I would far rather have a definitive statement from someone to the effect that if you do X, this will guarantee to find the memory cards and nothing else. For me, this is particularly important, as my application will be sold commercially and needs to work under all circumstances. David Hazel After our thread some weeks ago regarding reading the serial number from a MMC card, I've since implemented detection of the MMC card's presence by the existence of those same files. I know my solution works on my device perfectly. I figure it's probably a bad decision, because the architecture could change somewhat with the next hardware or software release. Can someone tell me, is there an approved / documented way of identifying the location of any MMC cards currently installed? I've noticed you can't simply look for /media/mmcX because that directory will exist even if there is no card inserted. Also, what determines MMC1 vs MMC2 as the card's path for internal/external? Is it possible these paths would change at some date? I know some Linux distro's with SATA drives had a problem with the drives changing their /dev/sdX path every reboot. I know that MY Nokia isn't doing anything similar, but I figure it's possible that my /media/mmc1 might be internal, but for someone else it could be the external slot - or maybe in the next hardware revision or something. I did find the alias names located in the /sys/ path that specify internal is for one and external or removable or something for the other. Also, are the names and paths the same for the 770's? Since I have an n800 I don't know. I'm hesitant to read too much data from /sys/ because it all looks _so_ Maemo-specific I wonder if I will tie my code too closely to one hardware revision. Just looking for the most _compatible_ way to identify if/when and where a media card is present. And as usual, from Python. Thanks, Tony ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
Re: Finding the mmc cards
ext Tony Maro [EMAIL PROTECTED] writes: Also, what determines MMC1 vs MMC2 as the card's path for internal/external? The internal card is always mounted on /media/mmc2, and the external card is always mounted on /media/mmc1. You can also use the environment variables MMC_MOUNTPOINT and INTERNAL_MMC_MOUNTPOINT, but then you have to make sure that they are always set correctly in your environment. (I don't think using environment variables for this kind of system information is a good idea.) The device files are not constant like this: the internal card might be /dev/mmcblk0 or /dev/mmcblk1, as far as I understand. Someone with better low-level knowledge please correct me. Is it possible these paths would change at some date? It is possible, but I guess we stick with these locations for a long time. We could and should provide mechanisms so that applications don't need to hardcode the locations, but I don't see a reason why we should break applications that do hardcode them. ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
Re: Finding the mmc cards
On 8/29/07, Marius Vollmer [EMAIL PROTECTED] wrote: The internal card is always mounted on /media/mmc2, and the external card is always mounted on /media/mmc1. And when the Nokia n900 (just guessing) gets released, and it has a memory stick socket or some other type of memory card, I assume we won't be able to rely on this anymore. But, sounds like for at least the short term (or long term in Internet years) relying on mount and /media/mmc* is the way to go. Assuming you don't need notifications of card insert. You can also use the environment variables MMC_MOUNTPOINT and INTERNAL_MMC_MOUNTPOINT, but then you have to make sure that they are always set correctly in your environment. (I don't think using environment variables for this kind of system information is a good idea.) Agreed. Especially with the numbers of morons like me that are likely to screw those up ;-) The device files are not constant like this: the internal card might be /dev/mmcblk0 or /dev/mmcblk1, as far as I understand. Someone with better low-level knowledge please correct me. I had thought this might be the case, especially since my /dev/mmcblk0 goes to /media/mmc2 and /dev/mmcblk1 goes to /media/mmc1 on my device. Seemed kind of reversed to me. ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
RE: Finding the mmc cards
I've added bug #1930. I hope I've done it right, because even that procedure isn't particularly clear. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Eero Tamminen Sent: 29 August 2007 10:40 To: ext [EMAIL PROTECTED] Cc: maemo-developers@maemo.org Subject: Re: Finding the mmc cards Hi, Please file a documentation bug into Maemo Bugzilla. We need this documented. Handling of removable medias, especially with file systems as easily corrupted as FAT, needs special care from applications (stop using files when pre-unmount message is delivered on them so that unmounts succeed, do better error handling etc.) - Eero ext [EMAIL PROTECTED] wrote: I agree that assuming mmc1 and mmc2 is potentially dangerous. In an answer to my original question on this subject, someone suggested that mmc0 and mmc1 were the correct names, whereas in my Scratchbox environment they are mmc1 and mmc2. Consequently, when I was implementing a scan for memory cards, I opted to look in the /media folder for files whose names begin mmc, and to assume that any such file I find might be a memory card. This appears to work (in the test/development environment), but personally I hate making those kinds of assumptions. I would far rather have a definitive statement from someone to the effect that if you do X, this will guarantee to find the memory cards and nothing else. For me, this is particularly important, as my application will be sold commercially and needs to work under all circumstances. David Hazel After our thread some weeks ago regarding reading the serial number from a MMC card, I've since implemented detection of the MMC card's presence by the existence of those same files. I know my solution works on my device perfectly. I figure it's probably a bad decision, because the architecture could change somewhat with the next hardware or software release. Can someone tell me, is there an approved / documented way of identifying the location of any MMC cards currently installed? I've noticed you can't simply look for /media/mmcX because that directory will exist even if there is no card inserted. Also, what determines MMC1 vs MMC2 as the card's path for internal/external? Is it possible these paths would change at some date? I know some Linux distro's with SATA drives had a problem with the drives changing their /dev/sdX path every reboot. I know that MY Nokia isn't doing anything similar, but I figure it's possible that my /media/mmc1 might be internal, but for someone else it could be the external slot - or maybe in the next hardware revision or something. I did find the alias names located in the /sys/ path that specify internal is for one and external or removable or something for the other. Also, are the names and paths the same for the 770's? Since I have an n800 I don't know. I'm hesitant to read too much data from /sys/ because it all looks _so_ Maemo-specific I wonder if I will tie my code too closely to one hardware revision. Just looking for the most _compatible_ way to identify if/when and where a media card is present. And as usual, from Python. Thanks, Tony ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
RE: Finding the mmc cards
You can also use the environment variables MMC_MOUNTPOINT and INTERNAL_MMC_MOUNTPOINT, but then you have to make sure that they are always set correctly in your environment. (I don't think using environment variables for this kind of system information is a good idea.) Those environment variables seem oddly inconsistent to an ex-VMS man like me. Why not EXTERNAL_MMC_MOUNTPOINT and INTERNAL_MMC_MOUNTPOINT? Otherwise it's necessary to remember which one the unqualified MMC_MOUNTPOINT refers to (e.g. by remembering that the other one starts with INTERNAL rather than EXTERNAL - which itself is counter-intuitive, as I would expect the internal one to be the more important and therefore the unqualified one). I also picked up on Tony's reply regarding the way in which /dev/mmcblk0 and /dev/mmcblk1 seem to be reversed in semantics with respect to the cards they relate to. With these two examples of inconsistency in card mappings, it seems all the more important to me that some kind of API is provided that can enumerate the cards with certainty (and with logical/naming consistency, please!) and can determine a range of useful information about the cards. Here are some ideas for the kind of information such an API might want to be able to retrieve: - serial number - capacity - whether FAT16 or FAT32 formatted - mountpoint - device file name - whether write protected (yes, you can write-protect an SD card) David Hazel ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
Re: Finding the mmc cards
On 8/29/07, David Hazel [EMAIL PROTECTED] wrote: - whether write protected (yes, you can write-protect an SD card) Yes, but the Nokia's do not support or honor that switch. ___ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
